15-101

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Questions and Answers

What is the primary purpose of the precipitation type nomogram shown in Figure 1.15?

To determine the precipitation type based on 1000 mb and 850 mb wet bulb temperatures (correct)

To calculate the snowfall accumulation vs. surface visibility

To identify the melting layer depth and mean layer temperature for freezing rain potential

To determine the probability of snowfall based on freezing level height

Which of the following is NOT a factor in determining the potential for freezing rain?

Surface visibility (correct)

Melting layer depth

Moisture into the dendritic layer

Mean layer temperature

What is the primary difference between the two precipitation type nomograms shown in Figures 1.15 and 1.16?

One is used for freezing rain and the other is used for sleet

One is used for warm air advection and the other is used for cold air advection

One is based on wet bulb temperatures and the other is based on thicknesses (correct)

One is used for heavy precipitation and the other is used for light precipitation

What is the main purpose of Figure 1.17?

To demonstrate the sounding for freezing drizzle Signup and view all the answers

According to Table 1.8, what is the relationship between snowfall accumulation and surface visibility?

There is an inverse correlation between snowfall accumulation and surface visibility Signup and view all the answers

What is the primary purpose of Tables 1.9-1.11?

To provide general rules of thumb for precipitation type forecasting Signup and view all the answers

Which of the following is a key factor in determining the potential for sleet?

Thickness values Signup and view all the answers

What is the main purpose of Figure 1.14?

To depict the typical freezing rain sounding Signup and view all the answers

What is the primary cause of pre- and post-frontal fog?

Rain falling into cold stable air and raising the dew point Signup and view all the answers

What is the minimum temperature required for ice fog to form?

-29°C (-20°F) Signup and view all the answers

What is the primary source of water vapor and pollutants that help to produce ice fog?

Burning hydrocarbon fuels, steam vents, motor vehicle exhausts, and jet exhausts Signup and view all the answers

What is the term for the transition from solid directly to vapor?

Sublimation Signup and view all the answers

What is the typical condition under which ice crystals sublime?

Low humidity and below-freezing conditions Signup and view all the answers

What contributes to the persistence of ice fog?

A strong low-level inversion Signup and view all the answers

What is the typical time of day when sublimation fog occurs?

At sunrise Signup and view all the answers

What is the typical condition under which front-passage fog occurs?

Warm and cold air masses are mixed by very light winds Signup and view all the answers

What is the main reason for the formation of dust storms in winter along the Arabian Peninsula, Red Sea, and equatorial regions of Africa?

Trade winds from the east converging with a polar high pressure system Signup and view all the answers

What is the typical wind speed range during dust storms in the Arabian Sea?

10-25 knots Signup and view all the answers

What is the primary characteristic of convective dust storms that makes them difficult to forecast?

Their small-scale phenomenon Signup and view all the answers

What is the role of hot air in the formation of dust devils?

It rises through the cooler air above Signup and view all the answers

What happens to the air at the bottom of a developing dust devil?

Hot air rushes in to replace the rising air Signup and view all the answers

Why do dust devils persist for a period of time?

Due to the supply of warm, unstable air Signup and view all the answers

What is the main danger posed by microbursts to aircraft?

Both reduced visibility and unpredictable wind gusts Signup and view all the answers

What is the shape of a dust devil once it is fully formed?

A narrow, funnel-like chimney Signup and view all the answers

What is the primary purpose of calculating the Mean Cloud Layer (MCL)?

To determine the base of convective clouds Signup and view all the answers

Which of the following techniques is used to forecast the base of cirrus clouds?

Tropopause method Signup and view all the answers

What is the primary factor in determining the turbulence category of an aircraft?

Wind speed Signup and view all the answers

What is the purpose of the Richardson Number calculation?

To determine the presence of turbulence Signup and view all the answers

What is the characteristic shape of a tropospheric temperature profile indicating potential turbulence?

S-shaped Signup and view all the answers

What is the primary cause of moderate CAT during the development of an upper-level low?

Surface cyclogenesis Signup and view all the answers

What is the purpose of the CCL Parcel Method?

To forecast the base of convective clouds Signup and view all the answers

What is the primary factor in determining the base of stratus clouds?

Dew point depression Signup and view all the answers

What is the primary factor that determines the height to which a haboob can ascend?

The strength of the convective outflow Signup and view all the answers

What is the typical duration of a haboob?

Up to 6 hours Signup and view all the answers

What is the primary purpose of the Air Force Weather's ensemble products?

To produce visibility probability products Signup and view all the answers

What is the characteristic of the lapse rate below the midlevel moisture surge in a haboob environment?

Dry adiabatic lapse rate Signup and view all the answers

What is the name of the index that indicates the most unstable lifted condition in a haboob environment?

Best lifted index Signup and view all the answers

What is the approximate percentage increase in peak winds in a haboob compared to the speed of movement?

95% greater Signup and view all the answers

What is the average distance that a haboob can travel?

60-90 miles Signup and view all the answers

What is the purpose of the AFW WEBSTBT ensembles page?

To display visibility probability products Signup and view all the answers

What is the radiation fog point determined by?

The intersection of the isohume with the surface Signup and view all the answers

What is the purpose of the radiation fog threat calculation?

To determine the likelihood of radiation fog formation Signup and view all the answers

What is the formula for the fog threat value?

WBPT850 - Fog Point Signup and view all the answers

What is the likelihood of radiation fog formation when the fog threat value is between 0 and 3?

Moderate Signup and view all the answers

How is the WBPT850 found if not already known?

By finding the pressure level of the 850 mb LCL and then lowering the parcel moist adiabatically to 1000 mb Signup and view all the answers

What is the primary purpose of Figure 1.4?

To demonstrate the WSCC example Signup and view all the answers

What is the purpose of the radiation fog stability index?

To determine the likelihood of radiation fog formation using a representative 1200Z sounding Signup and view all the answers

What is the unit of the WBPT850?

°C Signup and view all the answers

What is the primary application of Table 1.2?

To determine threshold dust-lofting wind speeds for different desert environments Signup and view all the answers

What is the primary difference between Figures 1.8 and 1.9?

Figure 1.8 shows visible comparison of dust detection capability, while Figure 1.9 shows infrared comparison Signup and view all the answers

What is the relationship between the fog threat value and the likelihood of radiation fog formation?

A higher fog threat value indicates a higher likelihood of radiation fog formation Signup and view all the answers

What is the primary purpose of Table 1.6?

To interpret the GEPS and MEPS Pollution Trapping Index (PTI) index Signup and view all the answers

What is the primary characteristic of Figure 1.11?

It illustrates overrunning associated with a typical cyclone Signup and view all the answers

What is the primary application of Figure 1.10?

To detect areas of atmospheric dust using the AOD product Signup and view all the answers

What is the primary difference between Table 1.4 and Table 1.5?

Table 1.4 shows fog threat thresholds, while Table 1.5 shows Fog Stability Index (FSI) thresholds Signup and view all the answers

What is the primary purpose of Figure 1.6?

To illustrate the OCDS-II example Signup and view all the answers

What is the phenomenon that causes haze particles to appear bluish when viewed against a dark background, but yellowish when viewed against a lighter background?

Mie scattering Signup and view all the answers

What is the primary factor that determines the visual range within a uniformly dense layer of haze?

Direction of the sun Signup and view all the answers

Which of the following areas is most conducive to haze formation?

Coastal areas Signup and view all the answers

What is the primary difference between smoke and haze?

Location of the particles Signup and view all the answers

What is the critical factor in determining the occurrence of blowing dust and sand?

All of the above Signup and view all the answers

What is the term for the particles that form through the condensation or sublimation of atmospheric water vapor?

Hydrometeors Signup and view all the answers

What is the primary difference between precipitation and blowing dust and sand?

Type of particles involved Signup and view all the answers

What is the primary factor in determining the type of hydrometeors that form?

Temperature Signup and view all the answers

Why is dust detection more difficult in infrared imagery at night?

The land cools, reducing the contrast between the dust and land. Signup and view all the answers

What is the reason for the improved dust detection in visible imagery over the Red Sea during the day?

The dark water background provides a high contrast with the dust. Signup and view all the answers

What is the effect of forward scattering on dust detection in visible satellite imagery?

It increases the reflection from dust, making it easier to detect. Signup and view all the answers

Why is the dust plume in Figure 1.9 more detectable at dawn?

The forward scattering of dust particles is more pronounced at dawn. Signup and view all the answers

What is the primary difference between dust detection in visible and infrared imagery?

Visible imagery detects dust over water, while infrared detects dust over land. Signup and view all the answers

What is the reason for the reduced thermal contrast between the dust and land at night?

The land cools, reducing the thermal contrast. Signup and view all the answers

What is the effect of backscattering on dust detection in visible satellite imagery?

It reduces the reflection from dust, making it harder to detect. Signup and view all the answers

Why is dust detection more difficult in infrared imagery over the Red Sea?

The dust is cooler than the underlying surface, reducing the thermal contrast. Signup and view all the answers

At what altitude does the potential haboob weaken?

Above 10,000 feet Signup and view all the answers

What is the purpose of examining thunderstorm and blowing dust climatology?

To determine the climatological likelihood of dust storms Signup and view all the answers

What type of soil is most prone to dust lofting?

Sandy soil Signup and view all the answers

At what level should you look for long wave troughs and ridges when analyzing the synoptic environment?

200-300 mb level Signup and view all the answers

What is the purpose of examining a recent soil moisture profile?

To determine where dust events are most likely to develop Signup and view all the answers

What is the purpose of determining the time period of interest?

To identify any dust events that may occur during this time period Signup and view all the answers

What is the purpose of consulting a chart of local soil types?

To determine which soil is most likely to be lofted Signup and view all the answers

What is the purpose of examining a recent dust source region database?

To couple climatology data with historical dust source region information Signup and view all the answers

What is the effect of down-welling IR radiation emitted by clouds on the fog layer during nighttime hours?

It mitigates some of the cooling of the fog layer from below. Signup and view all the answers

What is a favorable condition for the formation of advection fog?

Moist air advected over water cooled by upwelling. Signup and view all the answers

What is the term for fog that forms when warm, moist air is cooled to saturation as it moves over cold water?

Sea fog. Signup and view all the answers

What is the effect of wind speed on the depth of advection fog?

The depth of advection fog increases with increasing wind speed. Signup and view all the answers

What is the term for fog that forms when warm, moist air flows over colder land?

Advection-radiation fog. Signup and view all the answers

What is the characteristic shape of a developing dust devil?

Cylindrical. Signup and view all the answers

What is the primary factor that determines the persistence of advection fog?

Wind speed. Signup and view all the answers

What is the typical behavior of advection fog when it advects over warmer land?

It dissipates. Signup and view all the answers

Which of the following figures illustrates the CAT area along a shear line associated with an upper level low?

Figure 2.11 Signup and view all the answers

What is the primary purpose of Table 2.5?

To provide guidance on low-level turbulence Signup and view all the answers

Which of the following figures illustrates the mountain wave cloud structure?

Figure 2.16 Signup and view all the answers

What is the primary purpose of Figure 2.19?

To provide guidance on low-level turbulence forecasting Signup and view all the answers

Which of the following tables provides a guidance chart for low-level mountain wave turbulence?

Table 2.5 Signup and view all the answers

What is the primary purpose of Figure 2.21?

To provide guidance on low-level turbulence forecasting Signup and view all the answers

Which of the following tables provides a temperature difference vs. turbulence intensity chart?

Table 2.8 Signup and view all the answers

What is the primary purpose of Figure 2.20?

To provide guidance on convective cloud turbulence forecasting Signup and view all the answers

What is the primary factor in the deepening of the fog deck?

Turbulence within the fog deck Signup and view all the answers

What is the primary factor in the formation of coastal advection fog events?

Moisture convergence Signup and view all the answers

What is the effect of dry air aloft on the fog deck?

It deepens the fog deck and allows solar radiation to penetrate Signup and view all the answers

What is the result of light precipitation falling into a slightly unsaturated layer?

It leads to the formation of fog in the presence of warm fronts or cold fronts Signup and view all the answers

What is the primary factor in determining the degree of moisture convergence?

Converging winds and the advection of moisture Signup and view all the answers

What is the impact of the sun rising on the fog deck?

It lifts and dissipates the fog deck Signup and view all the answers

What is the primary role of moisture convergence in advection fog formation?

It is the primary factor in advection fog formation, especially along coastlines Signup and view all the answers

What is the effect of dry air aloft on the intensity of the fog deck?

It causes the intensity of the fog deck to fluctuate Signup and view all the answers

What is the typical height of a dust devil?

Between 500 and 1000 feet Signup and view all the answers

What is the primary reason for the formation of haboobs?

All of the above Signup and view all the answers

What is the effect of the downdraft air on the surrounding air?

It acts as a wedge that rapidly lifts the air Signup and view all the answers

What is the minimum temperature difference required for the downdraft air to continue to the surface unimpeded?

4°C Signup and view all the answers

What is the typical duration of a dust devil?

Up to an hour Signup and view all the answers

What is the typical diameter of a dust devil?

Between 10 and 300 feet Signup and view all the answers

In which region are haboobs most frequent?

Deserts of northern Africa Signup and view all the answers

What happens to the precipitation that falls into dry air in desert environments?

It evaporates Signup and view all the answers

What is the primary role of a wet surface in fog formation?

To increase the dew point of the planetary boundary layer Signup and view all the answers

Why are surface winds greater than 10 knots detrimental to fog formation?

They make it difficult for saturation to be achieved Signup and view all the answers

What is the primary importance of dry air above the surface for radiation fog development?

It allows the top of the fog deck to continue to cool via outgoing IR radiation Signup and view all the answers

What is the primary role of turbulence in the intensity and maintenance of the fog deck?

It plays a pivotal role in the intensity and maintenance of the fog deck Signup and view all the answers

What is the primary reason why radiation fog may not always have an advective source of surface moisture?

Because it forms without an ocean or lake nearby Signup and view all the answers

What is the primary consequence of surface winds greater than 10 knots on fog that has already formed?

They make it difficult for saturation to be achieved Signup and view all the answers

What is the primary factor that determines the formation of radiation fog?

The presence of dry air above the surface Signup and view all the answers

What is the primary consequence of dry air above the surface on the evolution of advection fog?

It allows the transition of advection fog to radiation fog Signup and view all the answers

What is the primary factor that affects the color of haze particles?

Background color Signup and view all the answers

What type of atmospheric layer is conducive to haze formation?

Stable atmospheric layer Signup and view all the answers

What is the main difference between smoke and other visibility restrictions?

Smoke is more localized Signup and view all the answers

What factors affect the critical wind speed for lifting dust and sand?

Vegetation, soil type, and soil moisture Signup and view all the answers

What is the term for the formation of frozen water lifted by the wind?

Hydrometeor Signup and view all the answers

What type of particles cause surface visibility reductions?

Hydrometeors Signup and view all the answers

What is the primary factor that determines the potential for visibility restrictions in industrial areas?

Presence of smoke sources Signup and view all the answers

What is the term for the process by which haze particles scatter light?

Mie scattering Signup and view all the answers

What is the purpose of publishing the Air Force Handbook 15-101?

To allow for more frequent updates and ensure review and approval of processes Signup and view all the answers

What is the benefit of hosting the handbook in the same location as other 15-series publications?

All of the above Signup and view all the answers

What is the limitation of the Air Force Handbook 15-101?

It is not a substitute for sound judgment and situationally relevant meteorological reasoning Signup and view all the answers

What is the purpose of the Air Force Handbook 15-101 in relation to meteorological techniques?

To provide general guidance for effective meteorological techniques Signup and view all the answers

What is the significance of the Air Force Handbook 15-101 in the Air Force Weather community?

It is a highly-esteemed reference in the Air Force Weather community Signup and view all the answers

What is the difference between the Air Force Handbook 15-101 and the legacy Field Operating Agency Technical Note 98/002?

The Air Force Handbook is a new publication, while the Technical Note is a legacy document Signup and view all the answers

In areas with a lack of vegetation, what occurs during the daytime due to the extreme heating?

Unstable boundary layers deepen, increasing the potential for dust lofting Signup and view all the answers

What can inhibit the formation of an inversion or remove one that has already formed?

Strong winds Signup and view all the answers

What is the role of the Air Force Handbook 15-101 in relation to additional Air Force guidance?

It is used in conjunction with additional Air Force guidance Signup and view all the answers

What is the threshold wind speed required for dust lofting in fine to medium sand in dune-covered areas?

10 to 15 mph Signup and view all the answers

What is the significance of the Air Force Handbook 15-101 in terms of its publication?

It is a formal publication of a long-lived and highly-esteemed reference Signup and view all the answers

What is the primary effect of a surface-based inversion on dust that is already suspended higher in the atmosphere?

It has little effect on dust that is already suspended Signup and view all the answers

What is the primary factor that determines the threshold wind speed required for dust lofting?

Type of desert environment Signup and view all the answers

What occurs after sunset in dry desert air due to strong radiative cooling?

Rapid heat loss Signup and view all the answers

What is the primary effect of strong winds on the formation of an inversion?

They inhibit the formation of an inversion Signup and view all the answers

What is the threshold wind speed required for dust lofting in well-developed desert pavement environments?

40 mph Signup and view all the answers

What is the primary purpose of Wind Stratified Conditional Climatologies (WSCC)?

To provide a baseline for constructing fog forecasts Signup and view all the answers

What type of data is shown in Figure 1.5?

Visibility less than 5 statute miles Signup and view all the answers

What is the purpose of Operational Climatic Data Summaries (OCDS-II)?

To generate plots of fog frequency, stratified by time of day and month of the year Signup and view all the answers

What is the radiation fog point?

The temperature at which radiation fog forms Signup and view all the answers

What is required to find the radiation fog point?

The pressure level of the LCL Signup and view all the answers

What is the output of WSCCs?

A percentage likelihood of a particular visibility category Signup and view all the answers

What is shown in Figure 1.4?

A WSCC example Signup and view all the answers

What is the purpose of the 14th Weather Squadron's library of climatological data?

To maintain a vast library of climatological data for various uses Signup and view all the answers

What is the primary cause of summer shamal dust storms?

Cold air advection aloft Signup and view all the answers

What is the typical height of summer shamal dust storms?

3000-8000 feet Signup and view all the answers

What is the primary source of wind that causes summer shamal?

Nocturnal low-level jet stream Signup and view all the answers

What is the typical duration of a summer shamal dust storm?

1-10 days Signup and view all the answers

What is the primary characteristic of winter shamal dust storms?

Associated with passing cold fronts Signup and view all the answers

What is the primary factor in the formation of winter shamal dust storms?

Cold air masses from Turkey or Syria Signup and view all the answers

What is the primary effect of a nocturnal radiational inversion on dust storms?

Traps dust particles near the surface Signup and view all the answers

What is the primary reason for the rapid reduction in visibility during a summer shamal dust storm?

Sudden increase in dust particles Signup and view all the answers

What is the primary mechanism responsible for dust plumes fanning out as they move downstream from their source regions?

Dispersion Signup and view all the answers

Which of the following conditions is favorable for dust storms when considering wind speed?

30 knots or greater Signup and view all the answers

What is the primary factor influencing the rate at which a dust plume disperses?

Turbulence Signup and view all the answers

Which of the following is NOT a dust removal mechanism?

Gravitational settling Signup and view all the answers

What is the typical time of day when dust storms are most likely to occur?

1200 to 1900L Signup and view all the answers

Which of the following agricultural practices is favorable for dust storms?

Soil left unprotected Signup and view all the answers

What is the primary effect of turbulence on a dust plume?

It increases the rate of dispersion Signup and view all the answers

Which of the following weather phenomena can generate blowing dust upstream?

All of the above Signup and view all the answers

What is the primary purpose of Figure 1.28?

To illustrate the daily atmospheric heating and cooling in relation to radiation gains and losses under clear skies Signup and view all the answers

What is the primary difference between the computations shown in Figure 1.29?

The presence or absence of an inversion Signup and view all the answers

What is the purpose of Table 1.18?

To provide K-value correction factors for the Callen and Prescott method Signup and view all the answers

What is the primary purpose of Table 1.20?

To show the relationship between wind chill and air temperature Signup and view all the answers

What is the primary purpose of Figure 1.30?

To provide a pressure conversion chart Signup and view all the answers

What is the primary purpose of Figure 1.31?

To provide a pressure altitude formula Signup and view all the answers

What is the primary purpose of Table 1.21?

To provide standard atmospheric pressure and temperature values by altitude Signup and view all the answers

What is the primary purpose of Table 1.23?

To provide altimeter settings Signup and view all the answers

What is the purpose of following an isohume down to the surface from the dew point at the LCL?

To determine the radiation fog point Signup and view all the answers

What is the formula to calculate the fog threat value?

WBPT850 - Fog Point Signup and view all the answers

What is the likelihood of radiation fog formation when the fog threat value is less than 0?

High Signup and view all the answers

What is the purpose of the radiation fog stability index?

To give the likelihood of radiation fog formation Signup and view all the answers

How is the WBPT850 found if not already known?

By lowering the parcel moist adiabatically to 1000 mb Signup and view all the answers

What is the unit of the WBPT850?

Degrees Celsius Signup and view all the answers

What is the purpose of Table 1.4?

To indicate the likelihood of radiation fog formation Signup and view all the answers

What is the purpose of finding the radiation fog point?

To calculate the fog threat value Signup and view all the answers

What is the primary role of surface winds in radiation fog formation?

To maintain a well-mixed planetary boundary layer Signup and view all the answers

Why is dry air above the surface important for radiation fog development?

It allows for radiative cooling of the earth's surface Signup and view all the answers

What happens to the air when the surface temperature cools to the dew point?

It becomes saturated Signup and view all the answers

What is the primary effect of dry air above the surface to great heights aloft?

It clears the skies Signup and view all the answers

Why is a wet surface important for radiation fog formation?

It serves as a source of moisture for the planetary boundary layer Signup and view all the answers

What is the primary role of turbulence generated by surface winds in radiation fog?

It intensifies fog Signup and view all the answers

What is the primary reason why surface winds greater than 10 knots are detrimental to fog formation?

They make it difficult for saturation to be achieved Signup and view all the answers

What happens to the top of the fog deck when dry air above the surface allows it to continue to cool via outgoing IR radiation?

It continues to cool and intensify Signup and view all the answers

What is the primary factor that indicates strong static stability between the surface and 850 mb, contributing to radiation fog formation?

Increasing temperatures with height Signup and view all the answers

What is the main purpose of the AFW Ensemble blowing dust forecasts?

To predict visibility less than five statute miles Signup and view all the answers

What is the characteristic of Satellite detection of dust at night?

Difficult to detect, especially in single channel imagery Signup and view all the answers

What is the purpose of the radiation fog stability index (FSI)?

To indicate radiation fog potential Signup and view all the answers

What is the relationship between the surface dew point and temperature when there is ample moisture in the layer?

The surface dew point is lower than the surface temperature Signup and view all the answers

What is the typical condition required for radiation fog formation?

Slow wind speeds at 850 mb and ample moisture in the layer Signup and view all the answers

What is the formula for the radiation fog stability index (FSI)?

FSI = 4TSfc - 2(T850 + TdSfc) + W850 Signup and view all the answers

What is the likelihood of radiation fog formation when the FSI is between 31 and 55?

Moderate Signup and view all the answers

What is the primary purpose of Figure 2.26?

To provide an authoritative upper level turbulence outlook Signup and view all the answers

What is the primary difference between rime icing and clear icing?

The smoothness of the ice surface Signup and view all the answers

What is the primary purpose of Table 2.9?

To provide a stratospheric layer advanced turbulence index Signup and view all the answers

What is the primary characteristic of cumuliform cloud icing?

It forms in cumulonimbus clouds Signup and view all the answers

What is the primary purpose of Figure 2.29?

To depict the characteristics of cumuliform cloud icing Signup and view all the answers

What is the primary difference between Figures 2.27 and 2.28?

The smoothness of the ice surface Signup and view all the answers

What is the primary purpose of Table 2.10?

To show the relationship between icing type and temperature Signup and view all the answers

What is the primary purpose of Figure 2.30?

To depict the characteristics of icing with a warm front Signup and view all the answers

What is the primary factor that determines the formation of fog?

Temperature difference between the air and the ground Signup and view all the answers

Which type of fog is formed when air is cooled adiabatically to its dew point?

Upslope fog Signup and view all the answers

What is the primary difference between upslope fog and radiation fog?

The mechanism of cooling Signup and view all the answers

What is the typical location for the formation of upslope fog?

Mountainous regions Signup and view all the answers

What is the primary factor that determines the persistence of upslope fog?

Lift and adiabatic cooling Signup and view all the answers

What is the name of the type of fog that forms when air is cooled to its dew point through the addition of moisture?

Frontal fog Signup and view all the answers

What is the term for fog that is composed of ice crystals?

Ice fog Signup and view all the answers

What is the primary factor that determines the formation of advection fog?

Wind speed and direction Signup and view all the answers

What is the primary reason why dust is easier to detect during the day than at night?

The sun provides a higher thermal contrast between the dust and the land Signup and view all the answers

What is the primary reason why dust is more difficult to detect over the Red Sea in infrared imagery?

The thermal contrast between the dust and the water is lower Signup and view all the answers

What is the effect of forward scattering on dust detection in visible satellite imagery?

It increases the detection of dust Signup and view all the answers

What is the primary reason why dust detection in visible satellite imagery at sunrise and sunset varies from detection during the day?

The forward and backscattering of dust particles Signup and view all the answers

What is the primary characteristic of the infrared image in Figure 1.8?

It shows dust over the land Signup and view all the answers

What is the primary reason why the dust cloud in Figure 1.9 is detectable at dawn?

The forward scattering of dust particles Signup and view all the answers

Why does the dust stand out over the dark water background in visible imagery?

Because the dust is more reflective than the water Signup and view all the answers

What is the primary difference between the visible and infrared images in Figure 1.8?

The ability to detect dust over land and water Signup and view all the answers

What is the primary role of a wet surface in fog formation?

It serves as a source of moisture for the planetary boundary layer Signup and view all the answers

Why are surface winds greater than 10 knots detrimental to fog formation?

They make it difficult for saturation to be achieved by maintaining a well-mixed PBL and bringing in drier ambient air Signup and view all the answers

What is the primary role of dry air above the surface in radiation fog development?

It allows the top of the fog deck to continue to cool via outgoing IR radiation Signup and view all the answers

What is the result of the surface temperature cooling to the dew point temperature?

The air becomes saturated and fog may form Signup and view all the answers

Why is a wet surface especially important for radiation fog formation?

Because it is not always present with an advective source of surface moisture Signup and view all the answers

What is the result of the turbulence generated by surface winds less than 10 knots?

It plays a pivotal role in the intensity and maintenance of the fog deck Signup and view all the answers

What is the characteristic of the air above the surface that is conducive to radiative cooling of the earth's surface?

Dry air with relative humidity less than 50% Signup and view all the answers

What is the effect of dry air above the surface on the fog deck?

It reinforces the fog deck and often causes it to intensify Signup and view all the answers

What is the primary purpose of Aerosol Optical Depth (AOD)?

To measure the amount of light that airborne particles prevent from passing through the atmosphere Signup and view all the answers

What is the primary factor in determining haboob potential from collapsing thunderstorms?

Cloud base height of the thunderstorm Signup and view all the answers

What is the primary purpose of surface climograms?

To provide a two-dimensional view of the likelihood of reduced visibility due to dust Signup and view all the answers

What is the primary indicator of potential reduced surface visibilities?

Aerosol Optical Depth (AOD) Signup and view all the answers

What is the primary factor in determining haboob potential from ongoing thunderstorms?

The strongest wind at any level aloft where the wet bulb potential temperature is less than the surface potential temperature Signup and view all the answers

What is the primary purpose of determining the cloud base height of a thunderstorm?

To forecast haboobs from ongoing thunderstorms Signup and view all the answers

What is the primary characteristic of a haboob environment?

Dry adiabatic lapse rates Signup and view all the answers

What is the primary purpose of forecasting haboobs from ongoing thunderstorms?

To issue timely warnings for reducing visibility due to dust Signup and view all the answers

What is the primary difference between whiteout conditions and fog?

Whiteout is a result of a uniformly overcast layer of clouds, whereas fog is a result of evaporation from the earth's surface. Signup and view all the answers

What is the primary cause of reduced visibility due to suspended water/ice particles?

Fog and mist Signup and view all the answers

What is the primary effect of whiteout conditions on low-level flights and landings?

They become more difficult due to reduced visibility and loss of depth perception. Signup and view all the answers

What is the primary characteristic of whiteout conditions?

Uniformly overcast layer of clouds Signup and view all the answers

What is the primary reason for the loss of depth perception in whiteout conditions?

The cloud layer breaks up and diffuses parallel rays from the sun. Signup and view all the answers

What is the primary difference between suspended liquid water particles and suspended solid water particles?

Suspended liquid water particles form clouds, whereas suspended solid water particles form fog. Signup and view all the answers

What is the primary effect of suspended water/ice particles on visibility?

They reduce visibility by restricting light transmission. Signup and view all the answers

What is the primary type of suspended water particles that is lifted by the wind from the earth's surface?

Drifting snow and blowing snow Signup and view all the answers

What is a necessary condition for the formation of mixed-phase fogs?

RH with respect to water is between 99% and 99.9% Signup and view all the answers

What is the minimum wind speed required for loose snow to become blowing snow?

10 to 15 knots Signup and view all the answers

What is the process by which precipitation falls through an unsaturated layer of air and eventually lowers the temperature to the wet-bulb temperature?

Wet-bulbing Signup and view all the answers

What reduces visibility in blowing snow, according to the rules of thumb?

Moderate, dry, and fluffy snowfall with wind speeds exceeding 15 knots Signup and view all the answers

What is the typical temperature range at which ice fog forms?

Less than -30°C Signup and view all the answers

What is the effect of introducing more fine particulates into surface air that is already very moist?

It allows supersaturation to be more easily achieved Signup and view all the answers

What type of fog is associated with a warm front?

Pre-frontal fog Signup and view all the answers

How is blowing snow encoded in surface aviation weather observations?

BS Signup and view all the answers

What is a common mechanism by which the surface air becomes saturated?

Temperature cooling to the dew point via cold air advection Signup and view all the answers

What determines the visibility in blowing snow?

Wind speed Signup and view all the answers

What is the composition of mixed-phase fogs?

Supercooled water droplets and ice crystals Signup and view all the answers

What happens to snow cover that has previously been subject to wind movement?

It does not produce as severe a visibility restriction as new snow Signup and view all the answers

What is the typical RH with respect to water for the formation of mixed-phase fogs?

Between 99% and 99.9% Signup and view all the answers

What is the effect of strong winds on snow that fell when temperatures were near freezing?

It blows only in very strong winds Signup and view all the answers

What is the effect of a wet ground surface on the air?

It allows the surface air to become saturated Signup and view all the answers

What is the definition of blowing snow?

Snow lifted from the surface of the earth by the wind to a height of 2 meters or more Signup and view all the answers

What is the primary factor that determines the duration of an advected dust?

Depth of the dust Signup and view all the answers

What is the primary reason for increased dust potential beyond 36 hours after a rainstorm?

Runoff after heavy rain carries soil particles Signup and view all the answers

What is the primary source of dust in agricultural areas?

Mechanical breaking of soil Signup and view all the answers

What is the primary factor that determines the wind direction in a dust storm?

Synoptic situations Signup and view all the answers

What is the primary reason for dust generation in deserts?

Low rainfall Signup and view all the answers

What is the primary way that dust is advected into an area?

By wind aloft Signup and view all the answers

What is the primary characteristic of dust source regions?

Low vegetation Signup and view all the answers

What is the primary factor that determines the potential for dust generation in coastal areas?

Cold frontal passages Signup and view all the answers

What is the primary purpose of Wind Stratified Conditional Climatologies (WSCC)?

To provide a baseline for constructing fog forecasts Signup and view all the answers

What type of data is available in a climogram?

Many weather parameters, including fog Signup and view all the answers

What is the primary purpose of Operational Climatic Data Summaries (OCDS-II)?

To generate plots of fog frequency Signup and view all the answers

What is the unit of the radiation fog point?

Celsius Signup and view all the answers

What is the first step in finding the radiation fog point?

Find the pressure level of the LCL Signup and view all the answers

What is the purpose of a surface climogram?

To determine the likelihood of fog Signup and view all the answers

What is the primary application of Wind Stratified Conditional Climatologies (WSCC)?

Fog forecasting in areas conducive to fog formation Signup and view all the answers

What is the relationship between the initial conditions and the output of Wind Stratified Conditional Climatologies (WSCC)?

The initial conditions determine the percentage likelihood of a particular visibility category Signup and view all the answers

What is the likely effect of clouds emitting down-welling IR radiation into a fog layer during nighttime hours?

The fog layer will slowly dissipate Signup and view all the answers

What is the typical wind speed above which advection fog is likely to lift into a low stratus cloud deck?

9 knots Signup and view all the answers

What is the primary characteristic of fog formed when warm, moist air flows over colder land?

Advection-radiation fog Signup and view all the answers

What is the condition necessary for sea fog formation?

The air is cooled to saturation as it moves over cold water Signup and view all the answers

What happens to sea fog if a change in wind direction carries the fog over a warmer surface?

The fog dissipates Signup and view all the answers

What is the typical location of advection fog formation during winter?

All of the above Signup and view all the answers

What is the primary factor influencing the depth of advection fog?

Wind speed Signup and view all the answers

What is the typical behavior of advection fog in the late afternoon?

It dissipates over warmer land Signup and view all the answers

What is the physical mechanism that lifts dust when a thunderstorm downdraft reaches the surface, causing a haboob?

Density current Signup and view all the answers

What is the primary difference between frontal dust storms and shamals?

Scale Signup and view all the answers

What type of jet stream is located behind a cold front?

Polar front jet stream Signup and view all the answers

What is the term for the prefrontal winds in Egypt?

Khamsin Signup and view all the answers

What is the average wind speed range for prefrontal dust storms?

10-20 knots Signup and view all the answers

What type of dust storm occurs across much of SWA as low pressure systems move across the region?

Prefrontal Signup and view all the answers

What is the term for the convergent area where the polar front jet stream and the subtropical jet stream meet?

Jet max Signup and view all the answers

What is the direction of prefrontal winds that are favored for prefrontal dust storms in October and November?

Easterly to southerly Signup and view all the answers

What is the primary purpose of the visibility definition provided by the American Meteorological Society?

To provide a standard for forecasting visibility Signup and view all the answers

What is the primary difference between haze and other dry obstructions?

Haze does not block light, but instead causes light rays to scatter Signup and view all the answers

What is the term for particles suspended in a dry atmosphere?

Lithometeors Signup and view all the answers

What is the primary purpose of the hail prediction chart?

To predict the size of hailstones Signup and view all the answers

What is the relationship between the WBZ height and the final hail size nomogram?

The WBZ height must be above 10,500 feet to use the nomogram Signup and view all the answers

What is the purpose of Table 3.12?

To relate VIL density to hail size Signup and view all the answers

What is the primary purpose of the glossary of references and supporting information?

To define key terms used in weather forecasting Signup and view all the answers

What is the primary benefit of using the Skew-T diagram for hail size prediction?

It is a graphical method for predicting hail size Signup and view all the answers

What is the typical relationship between MAXTEMP and SLR?

MAXTEMP is inversely proportional to SLR Signup and view all the answers

What is the primary difference between Figures 1.15 and 1.16?

The variables used to determine precipitation type Signup and view all the answers

What is the primary purpose of Figure 1.14?

To illustrate the typical sounding for freezing rain Signup and view all the answers

What is the primary factor in determining the potential for freezing precipitation?

The depth of the melting layer Signup and view all the answers

What is the primary purpose of Table 1.7?

To illustrate the probability of snowfall as a function of freezing level height Signup and view all the answers

What is the primary purpose of Figure 1.13?

To show the relationship between melting layer depth and mean layer temperature for freezing rain potential Signup and view all the answers

What is the primary difference between freezing rain and sleet?

The temperature at the surface Signup and view all the answers

What is the primary factor in determining the potential for drizzle?

The moisture in the dendritic layer Signup and view all the answers

What is the primary factor that contributes to the formation of sulfate aerosols?

Oxidation reactions enhanced by sunlight and/or liquid water Signup and view all the answers

What is the typical height range of the planetary boundary layer?

Up to 2 km Signup and view all the answers

What is the primary reason why haze can persist for days?

Absence of a cleansing mechanism such as precipitation Signup and view all the answers

What is the typical visibility range during haze conditions?

3 to 6 miles Signup and view all the answers

What is the primary characteristic of sulfate aerosols?

They are hygroscopic and absorb water from the environment Signup and view all the answers

What is the primary location where elevated layers of haze may occur?

Regions downstream from cumulus clouds Signup and view all the answers

What is the primary factor that contributes to the formation of haze in areas of high pressure?

Limited mixing and plenty of sun Signup and view all the answers

What is the primary boundary that marks the top of the planetary boundary layer?

Temperature inversion Signup and view all the answers

What is the primary purpose of releasing this handbook as a formal Air Force publication?

To enable more frequent updates of the document Signup and view all the answers

What is the primary goal of using meteorological techniques in the Air Force?

To provide general guidance for effective meteorological techniques Signup and view all the answers

What is the primary benefit of hosting the handbook in the same location as other 15-series publications?

To improve accessibility and organization of Air Force publications Signup and view all the answers

What is the primary reason for superseding the legacy Field Operating Agency Technical Note 98/002?

To formalize the document and enable more frequent updates Signup and view all the answers

Who certified the handbook?

Mr. Ralph O. Stoffler Signup and view all the answers

What is the page count of the handbook?

248 Signup and view all the answers

What is the releasability status of the handbook?

No releasability restrictions Signup and view all the answers

Where can Air Force personnel access the handbook?

The e-Publishing website Signup and view all the answers

What is the name of the wind that causes prefrontal dust storms in Egypt?

Khamsin Signup and view all the answers

What is the typical wind speed range during prefrontal dust storms?

10-20 knots Signup and view all the answers

What is the term for the physical mechanism that lifts dust during a dust storm?

Density current Signup and view all the answers

What is the direction of the prefrontal winds that are favored for prefrontal dust storms in October and November?

Easterly to southerly Signup and view all the answers

What is the location of the subtropical jet stream in relation to a cold front?

Ahead of a cold front Signup and view all the answers

What is the primary difference between shamals and frontal dust storms?

Scale Signup and view all the answers

What is the name of the wind that causes prefrontal dust storms in Iraq?

Sharqi Signup and view all the answers

What contributes to the increase in upward vertical velocities during prefrontal dust storms?

Ageostrophic circulations Signup and view all the answers

What is the primary purpose of Wind Stratified Conditional Climatologies (WSCC) in fog forecasting?

To indicate the percentage likelihood of a particular visibility category Signup and view all the answers

What type of plot does the Operational Climatic Data Summaries (OCDS-II) web application enable users to generate?

Fog frequency plot stratified by time of day and month of the year Signup and view all the answers

What is the unit of the radiation fog point?

°C Signup and view all the answers

What is the purpose of finding the pressure level of the LCL in relation to the radiation fog point?

To find the temperature at which radiation fog forms Signup and view all the answers

What type of climatological data is depicted in Figure 1.5?

Visibility climogram Signup and view all the answers

What is the primary application of the Wind Stratified Conditional Climatologies (WSCC) in fog forecasting?

To construct fog forecasts in areas conducive to fog formation Signup and view all the answers

What is the primary difference between a climogram and a WSCC?

A climogram shows the likelihood of an event's occurrence, while a WSCC shows the percentage likelihood of a particular visibility category Signup and view all the answers

What is the primary purpose of the 14th Weather Squadron?

To operate and maintain a vast library of climatological data Signup and view all the answers

What does Aerosol Optical Depth (AOD) provide as a first-order indicator of?

Potential reduced surface visibilities Signup and view all the answers

What is required to forecast haboobs from ongoing thunderstorms?

High mid-level moisture and dry adiabatic lapse rates Signup and view all the answers

What is the primary factor in determining haboob potential from collapsing thunderstorms?

Cloud base height of the thunderstorm Signup and view all the answers

What is the typical condition under which thunderstorm collapse is most likely to occur?

After sunset when buoyancy diminishes Signup and view all the answers

What is the purpose of a surface climogram product?

To aid in dust forecasting by providing a two-dimensional view of the likelihood of reduced visibility due to dust Signup and view all the answers

What is required to bring strong winds to the surface in a haboob environment?

A strong wind at any level aloft where the wet bulb potential temperature is less than the surface potential temperature by at least 4°C Signup and view all the answers

What is the primary purpose of Figure 1.10?

To display the Aerosol Optical Depth (AOD) product Signup and view all the answers

What is the characteristic of the lapse rate below the mid-level moisture surge in a haboob environment?

Steep and dry adiabatic Signup and view all the answers

What is the primary source region for many dust storms, particularly during shamal events?

River flood plains of the Tigris and Euphrates Rivers Signup and view all the answers

What is the minimum wind speed required to mobilize dust particles?

15 knots Signup and view all the answers

What is necessary for dust lofting, in addition to wind?

Both A and B Signup and view all the answers

What is the typical wind speed range at 1000 feet necessary to keep dust particles aloft?

30-40 knots Signup and view all the answers

What is the primary characteristic of the soils formed from water in lakes?

They inhibit plant growth and blow easily in strong winds Signup and view all the answers

What is the size range of the first sand and dust particles that move in strong winds?

0.08-1 mm Signup and view all the answers

What is the primary reason why dust storms can maintain their intensity even after wind speeds slow down?

The bond between dust particles and the surface is already broken Signup and view all the answers

What is the term for the wind that blows over Iraq and the Persian Gulf states, particularly during dust storm generation?

Shamal Signup and view all the answers

What is the main difference between a single cell thunderstorm and a supercell thunderstorm?

The presence of a mesocyclone Signup and view all the answers

Which type of synoptic pattern is most conducive to the development of severe thunderstorms?

Type A - Dryline Signup and view all the answers

What is the term for a brief, intense downdraft that can cause strong winds and damage?

Microburst Signup and view all the answers

Which of the following figures shows the atmospheric profiles associated with microbursts?

Figure 3.7 Signup and view all the answers

What is the primary factor in determining the potential for severe thunderstorm development?

Mid-level wind shear Signup and view all the answers

Which of the following types of supercells is characterized by heavy precipitation?

High-precipitation supercell Signup and view all the answers

What is the primary purpose of Table 3.1?

To determine the potential for severe thunderstorm development Signup and view all the answers

Which of the following figures shows the characteristic shape of a classic supercell?

Figure 3.4 Signup and view all the answers

Under which conditions would dense sea fog persist even with high winds?

Over very cold water Signup and view all the answers

What is the primary step in making a good radiation fog forecast?

Predicting the nighttime minimum temperature Signup and view all the answers

What happens to the fog when sea fog moves onshore to warmer land?

It rapidly dissipates Signup and view all the answers

What is the effect of wind speeds of 3-7 knots on radiation fog?

It brings more moist air in contact with the cool surface, causing the fog layer to thicken Signup and view all the answers

What is the result of further heating of a stratus layer?

It changes into convective clouds or dissipates entirely Signup and view all the answers

What is the effect of cooling after the heat of the day on sea fog?

It causes sea fog to roll back in and restrict ceilings and visibility Signup and view all the answers

What is the condition necessary for radiation fog to occur?

Air with a high dew point Signup and view all the answers

What happens to the dew-point temperature of the air when the ground surface is dry in the early evening?

It may drop slightly during the night due to condensation of some water vapor as dew or frost Signup and view all the answers

What is the primary factor that contributes to the formation of front-passage fog?

Mixing of warm and cold air masses Signup and view all the answers

What is the typical temperature range required for ice fog to form?

–29°C (–20°F) and colder Signup and view all the answers

What is the primary source of water vapor and pollutants that help to produce ice fog?

Burning hydrocarbon fuels and steam vents Signup and view all the answers

What is the primary condition under which ice crystals sublime?

Low humidity in below-freezing conditions Signup and view all the answers

What is the primary cause of sublimation fog?

Ground frost subliming at sunrise Signup and view all the answers

What is the primary factor that contributes to the persistence of ice fog?

Strong low-level inversion Signup and view all the answers

What is the primary difference between pre- and post-frontal fog and front-passage fog?

Pre- and post-frontal fog is caused by rain falling into cold stable air, while front-passage fog is caused by mixing of warm and cold air masses Signup and view all the answers

What is the primary characteristic of ice fog?

It is composed of ice crystals Signup and view all the answers

What is the primary factor that contributes to the formation of a surface-based inversion in dry desert air?

Rapid heat loss after sunset Signup and view all the answers

What is the threshold wind speed required for dust lofting in areas with well-developed desert pavement?

40 mph Signup and view all the answers

How does the formation of a surface-based inversion impact dust that is already suspended higher in the atmosphere?

It has little effect on dust lofting Signup and view all the answers

What is the primary factor that determines the threshold wind speed for dust lofting in different desert environments?

The size of the sand particles Signup and view all the answers

What is the effect of strong winds on the formation of a surface-based inversion?

They remove an inversion that has already formed Signup and view all the answers

What is the primary reason for the diurnal variation in dust storm potential?

The change in temperature during the day Signup and view all the answers

What is the primary impact of a stable boundary layer on dust lofting?

It inhibits dust lofting Signup and view all the answers

What is the primary factor that determines the depth of an unstable boundary layer?

The amount of heating Signup and view all the answers

What is the effect of dry air aloft on the fog deck?

It allows for maximum heating of the fog deck and causes it to deepen Signup and view all the answers

What is the primary factor in coastal advection fog events?

Moisture convergence Signup and view all the answers

What occurs when precipitation falls into a slightly unsaturated layer?

Surface relative humidity with respect to water reaches 100% or slight supersaturation Signup and view all the answers

What is the role of winds within the residual layer (RL) in fog formation?

They enhance the mixing of dry air into the fog deck Signup and view all the answers

What is the primary purpose of moisture convergence?

To measure the degree to which moist air is converging into a given area Signup and view all the answers

What is the effect of solar radiation on the fog deck?

It permits the fog deck to lift and dissipate when IR cooling is no longer sufficient to maintain the fog Signup and view all the answers

What is the primary location where moisture convergence occurs?

All of the above Signup and view all the answers

What is the result of light precipitation falling into a slightly unsaturated layer?

Fog formation often leads to fog events in the presence of warm fronts, cold fronts, or other convergent boundaries Signup and view all the answers

What should be used to refer recommended changes and questions about this publication?

Air Force Form 847 Signup and view all the answers

What is the purpose of maintaining records created as a result of processes prescribed in this publication?

To ensure compliance with Air Force Records Information Management System Records Disposition Schedule Signup and view all the answers

What does the use of a specific manufacturer, commercial product, commodity, or service in this publication imply?

No endorsement or rejection by the Air Force Signup and view all the answers

What is the basis of the creation of this Handbook?

The 2012 tech note revision Signup and view all the answers

What should be reviewed completely due to the substantial revision of the document?

The entire Handbook Signup and view all the answers

What has been updated to reflect advanced processes and procedures?

Numerous techniques Signup and view all the answers

What has been modernized with improved graphics and pictures?

Many illustrations and figures Signup and view all the answers

What is the typical format of the table of contents and list of topics in this Handbook?

Similar to the 2012 tech note revision Signup and view all the answers

What is the primary purpose of Figure 2.1?

To depict the cloud-free plot over China and East Asia Signup and view all the answers

What is the main factor in determining the turbulence category of an aircraft?

The Richardson Number calculation Signup and view all the answers

What is the primary purpose of Table 2.2?

To display the aircraft turbulence category type Signup and view all the answers

What is the characteristic shape of a tropospheric temperature profile indicating potential turbulence?

S-shaped Signup and view all the answers

What is the primary purpose of Figure 2.5?

To display the stratus dissipation technique Signup and view all the answers

What type of wind pattern is associated with the CAT area shown in Figure 2.12?

Diffluent wind pattern Signup and view all the answers

What is the primary cause of moderate CAT during the development of an upper-level low?

The surface cyclogenesis and jet-core Signup and view all the answers

What is the primary purpose of Table 2.5?

To determine the likelihood of mountain wave turbulence Signup and view all the answers

What is the primary purpose of the CCL Parcel Method?

To predict the base of convective clouds Signup and view all the answers

What type of cloud structure is shown in Figure 2.16?

Mountain wave cloud structure Signup and view all the answers

What is the primary factor in determining the base of stratus clouds?

The dew point depression of the surface Signup and view all the answers

What is the primary purpose of Figure 2.19?

To provide guidance on low-level turbulence for Category II aircraft Signup and view all the answers

What is the primary factor in determining the turbulence intensity according to Table 2.7?

Surface-9000 foot temperature difference Signup and view all the answers

What is the primary purpose of Figure 2.21?

To provide guidance on low-level turbulence for Category II aircraft Signup and view all the answers

What is the primary characteristic of the wind pattern shown in Figure 2.14?

Wind maximum to the rear of the upper trough Signup and view all the answers

What is the primary purpose of Table 2.6?

To provide guidance on expected turbulence locations Signup and view all the answers

What is the primary purpose of Figure 2.47?

To show the relationship between temperature and emitted energy. Signup and view all the answers

What is the primary factor that determines the physical temperature of an object?

Emissivity Signup and view all the answers

What type of scattering occurs when the scatterer size is larger than the wavelength of light?

Mie scattering Signup and view all the answers

What is the primary effect of weather on EO sensors according to Table 2.17?

Decrease in signal strength Signup and view all the answers

What is the primary purpose of Figure 2.52?

To show the effect of sun angle on EO sensors Signup and view all the answers

What is the primary application of Figure 2.49?

To determine the type of scattering based on wavelength and scatterer size Signup and view all the answers

What is the primary characteristic of thermal crossover?

Difference between inherent and apparent contrast Signup and view all the answers

What is the primary purpose of Table 2.16?

To show the relationship between emissivity and physical/radiative temperatures Signup and view all the answers

What is the primary purpose of Table 1.1?

To provide visibility limits based on snowfall intensity Signup and view all the answers

What is the primary purpose of Figure 1.5?

To provide a Visibility Climogram example for Vandenberg AFB Signup and view all the answers

What is the primary purpose of Table 1.4?

To provide fog threat thresholds Signup and view all the answers

What is the primary purpose of Figure 1.10?

To show the AOD product, highlighting areas of atmospheric dust Signup and view all the answers

What is the primary purpose of Table 1.6?

To provide interpretation of the GEPS and MEPS Pollution Trapping Index (PTI) index Signup and view all the answers

What is the primary purpose of Figure 1.11?

To show overrunning associated with a typical cyclone Signup and view all the answers

What is the primary purpose of Figure 1.8?

To show the difference between visible and infrared detection of dust Signup and view all the answers

What is the primary purpose of Figure 1.9?

To show sunrise dust plume detection, due to forward scattering Signup and view all the answers

What is the physical mechanism that lofts dust when a thunderstorm downdraft reaches the surface, causing a haboob?

Density current Signup and view all the answers

What is the term for the winds that occur ahead of a cold front and are associated with prefrontal dust storms?

Easterly to southerly winds Signup and view all the answers

What is the characteristic wind speed range during prefrontal dust storms?

10-20 knots Signup and view all the answers

What is the location of the jet stream that converges into a single jet streak, contributing to prefrontal dust storms?

Ahead of a cold front Signup and view all the answers

What is the type of circulation that increases upward vertical velocities, enhancing the probability of dust lofting?

Ageostrophic circulation Signup and view all the answers

What is the term for the dust storms that occur with synoptic-scale systems, carrying sand particles over large distances?

Frontal dust storms Signup and view all the answers

What is the name of the winds in Iraq that are associated with prefrontal dust storms?

Sharqi Signup and view all the answers

What is the typical duration of prefrontal dust storms?

Short-lived, rarely more than a few hours Signup and view all the answers

What does a low FSI value indicate regarding radiation fog formation?

Low likelihood Signup and view all the answers

What is the purpose of the GEPS and MEPS products on AFW-WEBS?

Forecasting blowing dust probability Signup and view all the answers

What makes satellite detection of dust difficult?

Single channel imagery Signup and view all the answers

What is the purpose of animated infrared imagery in dust detection?

Identifying the location of dust plumes Signup and view all the answers

What is the term for the FSI formula?

Fog Stability Index Signup and view all the answers

What is the primary factor in radiation fog formation indicated by the FSI?

All of the above Signup and view all the answers

What is the purpose of the AFW Ensemble blowing dust forecasts?

Forecasting blowing dust probability Signup and view all the answers

What can be used to track dust over land during the day?

Animated infrared imagery Signup and view all the answers

What is the purpose of determining the radiation fog point?

To determine the likelihood of radiation fog formation Signup and view all the answers

How is the WBPT850 found if not already known?

By lowering the parcel moist adiabatically to 1000mb from the pressure level of the 850mb LCL Signup and view all the answers

What is the likelihood of radiation fog formation when the fog threat value is less than 0?

High Signup and view all the answers

What is the purpose of the radiation fog stability index?

To give the likelihood of radiation fog formation using a representative 1200Z sounding Signup and view all the answers

What is the formula for the fog threat value?

WBPT850 - Fog Point Signup and view all the answers

What is the unit of the WBPT850?

°C Signup and view all the answers

How is the radiation fog point determined?

By following an isohume down to the surface from the dew point at the LCL Signup and view all the answers

What is the purpose of Table 1.4?

To give the thresholds for radiation fog formation Signup and view all the answers

What is the typical height of a dust devil?

500 to 1000 feet Signup and view all the answers

What is the main reason for the formation of haboobs?

Evaporation of precipitation in dry air Signup and view all the answers

What is the effect of the downdraft air on the surrounding air in a haboob?

It makes the surrounding air colder and denser Signup and view all the answers

What is the typical duration of a haboob?

Up to an hour Signup and view all the answers

What is the typical direction of the spread of haboob air?

In the direction of the low-level winds Signup and view all the answers

What is the minimum temperature difference required for the downdraft air to reach the surface?

4°C Signup and view all the answers

What is the effect of the haboob air on the surrounding environment?

It cools the surrounding air Signup and view all the answers

What is the typical region where haboobs are most frequent?

Deserts of northern Africa Signup and view all the answers

What is the primary factor that determines the duration of advected dust?

Depth of the dust Signup and view all the answers

What is the most likely region to experience dust storms after a rainstorm?

Deserts Signup and view all the answers

What is the primary reason for dust generation in agricultural areas?

Mechanical breaking of soil Signup and view all the answers

What is the primary characteristic of dust storms generated in coastal areas?

Dust plumes generated in advance of cold fronts Signup and view all the answers

What is the primary factor that determines the probability of dust advecting into an area?

Synoptic situation Signup and view all the answers

What is the primary condition required for dust storms to occur?

Little vegetation and precipitation Signup and view all the answers

What is the primary reason for increased dust potential beyond 36 hours after a rainstorm?

Runoff after heavy rain Signup and view all the answers

What is the primary purpose of Figure 2.4?

To calculate the Cloud Condensation Level (CCL) Signup and view all the answers

What is the primary factor in determining the turbulence category of an aircraft?

Wind shear and direction Signup and view all the answers

What is the characteristic shape of a tropospheric temperature profile indicating potential turbulence?

S-shaped profile Signup and view all the answers

What is the primary cause of moderate CAT during the development of an upper-level low?

Jet-core interaction Signup and view all the answers

What is the primary purpose of the Richardson Number calculation?

To assess the stability of the atmosphere Signup and view all the answers

What is the primary factor in determining the base of stratus clouds?

Mixing ratio and temperature Signup and view all the answers

What is the primary purpose of Figure 2.3?

To calculate the Mean Cloud Layer (MCL) Signup and view all the answers

What is the primary factor in determining the expected bases of convective clouds?

Surface dew point depression Signup and view all the answers

What is the primary purpose of Figure 2.35?

To depict the typical icing areas in a mature cyclone Signup and view all the answers

What is the primary factor in determining icing potential based on temperature and dew point depression?

Temperature-dew point spread Signup and view all the answers

What is the primary purpose of the Appleman chart in Figure 2.41?

To forecast contrail formation Signup and view all the answers

What is the primary difference between the GALWEM no-bypass and high-bypass forecast products?

Engine type Signup and view all the answers

What is the primary purpose of Table 2.13?

To identify engine bypass types for military aircraft Signup and view all the answers

What is the primary purpose of Figure 2.36?

To provide a flowchart for icing determination Signup and view all the answers

What is the primary factor in determining the potential for contrail formation?

Air temperature Signup and view all the answers

What is the primary purpose of Figure 2.38?

To depict the increasing flight level winds with CAA Signup and view all the answers

What is the primary difference between blowing snow in polar regions and mid-latitudes?

Snow is colder, dry, fine, and easily lifted in polar regions Signup and view all the answers

What is the minimum temperature required for fresh snow to blow or drift?

–20°C (–4°F) Signup and view all the answers

What happens to snow after 3 or more days of exposure to direct sunlight?

It forms a crust and does not readily drift or blow Signup and view all the answers

What is the effect of terrain undulations, shadows, and vegetation on snow crust formation?

They retard the formation of the crust Signup and view all the answers

What happens to the visibility when winds raise the snow 1000 feet above the ground?

It decreases to near zero Signup and view all the answers

What is the primary constituent of haze droplets over industrial areas?

Sulfuric acid Signup and view all the answers

What is the primary reason why prefrontal dust storms are difficult to detect in METSAT imagery?

Because they are short-lived and often located over similarly shaded terrain Signup and view all the answers

What is the effect of additional snow falling onto snowpack that has already crusted?

Only the new snow blows or drifts Signup and view all the answers

What is the typical height reached by postfrontal dust storms?

8,000-15,000 feet Signup and view all the answers

What is the average wind speed associated with postfrontal dust storms?

15-30 knots Signup and view all the answers

What is the purpose of Table 1.1?

To forecast visibility based on snowfall intensity Signup and view all the answers

How can wind speed be estimated in postfrontal dust storms?

By the temperature change across the front Signup and view all the answers

What is the duration of the first type of postfrontal dust storms?

24-36 hours Signup and view all the answers

What occurs along the stationary boundary in the second type of postfrontal dust storms?

Cyclogenesis occurs Signup and view all the answers

What is the typical direction of movement of the cold front in postfrontal dust storms?

East-northeast Signup and view all the answers

What is the typical time it takes for the dust to move across the Persian Gulf in postfrontal dust storms?

12-24 hours Signup and view all the answers

What is the typical diameter range of dust devils?

10 to 300 feet Signup and view all the answers

What is the primary factor that drives the persistence of dust devils?

Intense convection Signup and view all the answers

What is the typical height range of dust devils?

500 to 1000 feet Signup and view all the answers

What is the primary characteristic of haboobs that distinguishes them from other types of dust storms?

Convective outflow from a collapsing or ongoing thunderstorm Signup and view all the answers

What is the primary effect of precipitation on the air in a desert environment?

Evaporation of the precipitation cools the air Signup and view all the answers

What is the primary reason why the air at the surface is colder and denser than the ambient air in a haboob?

The air at the surface is cooled by evaporation Signup and view all the answers

What is the primary direction of air movement in a haboob?

In the direction of the low-level winds Signup and view all the answers

What is the minimum temperature difference required for the air to continue to the surface unimpeded in a haboob?

4°C Signup and view all the answers

What is the typical range of relative humidity with respect to water for the formation of mixed-phase fogs?

99% to 99.9% Signup and view all the answers

What is the minimum temperature required for ice fog to form?

-30°C Signup and view all the answers

What is the process by which precipitation falls through an unsaturated layer of air, eventually lowering the temperature to the wet-bulb temperature?

Wet-bulbing Signup and view all the answers

What is the effect of introducing more fine particulates into surface air that is already very moist?

It increases the likelihood of fog formation Signup and view all the answers

What is the primary mechanism by which the surface air becomes saturated?

All of the above Signup and view all the answers

What is the primary cause of buoyancy turbulence in the atmosphere?

Parcels of air rising during the diurnal heating of the surface Signup and view all the answers

What is the primary characteristic of mixed-phase fogs?

They are composed of supercooled water droplets and ice crystals Signup and view all the answers

What is the effect of a wet ground surface on fog formation?

It increases the likelihood of fog formation Signup and view all the answers

What is the primary mechanism by which precipitation removes dust from the troposphere?

Dust particles form the nucleus of precipitation, which then falls to the ground Signup and view all the answers

What is the primary characteristic that distinguishes a shamal from other types of dust storms?

Strong winds blowing from the north Signup and view all the answers

What is the primary factor in determining the formation of ice fog?

Relative humidity Signup and view all the answers

What is the term for the process by which dust is moved away from its source?

Advection Signup and view all the answers

What is the primary difference between the wind direction at the surface and aloft?

The wind direction is different at the surface and aloft due to differences in wind speed Signup and view all the answers

What is the primary reason why dust that leaves the ground going one direction can rise to a level where it travels in an entirely different direction?

Dust is affected by wind shear Signup and view all the answers

What is the primary effect of precipitation on dust particles?

Precipitation removes dust particles from the troposphere Signup and view all the answers

What is the typical location where the summer shamal occurs?

In the Middle East and Arabian Peninsula Signup and view all the answers

What typically obscures prefrontal dust storms from METSAT view?

Cloud cover due to pre-cold frontal overrunning Signup and view all the answers

What is the typical height reached by postfrontal dust storms?

8,000-15,000 feet Signup and view all the answers

What is the maximum wind speed corresponding to a temperature change of 10°C across a front?

30 knots Signup and view all the answers

How long does the first type of postfrontal dust storm typically last?

24-36 hours Signup and view all the answers

What is the typical time it takes for dust to move across the Persian Gulf?

12-24 hours Signup and view all the answers

What occurs along the stationary boundary in the second type of postfrontal dust storm?

Frontal waves moving to the east-northeast Signup and view all the answers

What is the average surface wind speed during a postfrontal dust storm?

15-30 knots Signup and view all the answers

What can cause wind speeds of 40-50 knots in postfrontal dust storms?

Very strong low pressure systems Signup and view all the answers

What is the primary reason for the yellowish color of haze particles when viewed against a lighter background?

Mie scattering phenomenon Signup and view all the answers

Which of the following is a characteristic of smoke that affects visibility forecasts?

It is localized and dependent on local terrain and wind patterns Signup and view all the answers

What is the critical factor in determining the wind speed required to lift dust and sand?

Vegetation, soil type, and soil moisture Signup and view all the answers

What is the term for atmospheric water vapor that forms particles through condensation or sublimation?

Hydrometeor Signup and view all the answers

Which of the following is a type of hydrometeor that causes surface visibility reductions?

Precipitation Signup and view all the answers

What is the primary factor that determines the visibility range within a uniformly dense layer of haze?

The direction of the sun Signup and view all the answers

Which of the following areas is most conducive to haze formation?

Coastal areas Signup and view all the answers

What is the primary effect of haze on visibility?

It reduces visibility Signup and view all the answers

What is the primary force responsible for the formation of geostrophic wind?

Coriolis force Signup and view all the answers

What is the primary characteristic of open-cell cumulus clouds?

They have a random, irregular shape Signup and view all the answers

What is the primary purpose of Table 1.13?

To calculate wind speed adjustments based on elevation Signup and view all the answers

What is the primary factor influencing the shape of the coastline on sea breeze divergence or convergence?

Coastline orientation Signup and view all the answers

What is the primary application of Figure 1.26?

To illustrate the formation of von Karman vortices Signup and view all the answers

What is the primary purpose of Table 1.14?

To determine the crosswind component Signup and view all the answers

What is the primary factor influencing the formation of stratocumulus lines over the Alaskan Peninsula?

Moisture content Signup and view all the answers

What is the primary purpose of Table 1.17?

To calculate wind speed and wind gust using the 1.4 multiplier Signup and view all the answers

At what temperature and dew point depression is icing most likely to occur?

Between -5°C and 0°C and 2°C dew point depression Signup and view all the answers

What is the purpose of the '-8D Method' shown in Figure 2.37?

To determine the icing potential Signup and view all the answers

What is the primary purpose of Figure 1.28?

To illustrate the daily atmospheric heating and cooling in relation to radiation gains and loses under clear skies Signup and view all the answers

What is the primary factor in determining the formation of contrails?

Engine type and altitude Signup and view all the answers

What is the purpose of the GALWEM forecast product shown in Figure 2.43?

To forecast wind patterns Signup and view all the answers

What is the primary purpose of Tables 1.18 and 1.19?

To provide K-value correction factors for the Callen and Prescott method and the McKenzie method Signup and view all the answers

What is the primary purpose of Figure 1.30?

To provide a pressure conversion chart Signup and view all the answers

What is the primary use of Table 2.13?

To determine engine bypass type for military aircraft Signup and view all the answers

What is the primary purpose of Figure 2.35?

To show typical icing areas in a mature cyclone Signup and view all the answers

What is the primary purpose of Figure 1.31?

To provide a pressure altitude formula Signup and view all the answers

What is the primary purpose of Tables 1.21 and 1.22?

To show the standard atmospheric pressure and temperature by altitude and by level Signup and view all the answers

What is the primary purpose of Figure 2.34?

To show carburetor icing potential Signup and view all the answers

What is the primary use of Figure 2.36?

To determine icing potential Signup and view all the answers

What is the primary purpose of Table 1.23?

To provide altimeter settings Signup and view all the answers

What is the primary purpose of Table 1.20?

To provide a wind chill temperature chart Signup and view all the answers

What marks the beginning of Chapter 2?

Page 91 Signup and view all the answers

At what altitude does the potential haboob weaken?

Greater than 10,000 feet Signup and view all the answers

What happens to the air when light precipitation falls into an unsaturated layer?

It cools and moistens Signup and view all the answers

What is the primary purpose of examining a recent soil moisture profile?

To determine which soil types are most likely to be lofted Signup and view all the answers

What feature is indicative of an imminent collapse in infrared satellite imagery?

Rapidly warming cloud tops Signup and view all the answers

Under which condition is fog formation rare?

Statically or conditionally unstable atmosphere Signup and view all the answers

What is the effect of warm air advection on the duration of fog?

It lengthens the duration of fog Signup and view all the answers

What type of soils drain easier and are more prone to dust lofting?

Sandy soils Signup and view all the answers

What is the typical atmospheric condition under which fog forms?

Surface anticyclone Signup and view all the answers

What do you consult to determine the climatological likelihood of dust storms at your location?

The 14th Weather Squadron Signup and view all the answers

What do you examine to determine where dust events are most likely to develop?

Recent dust source region database Signup and view all the answers

What is the role of surface dew points in fog formation?

High surface dew points are not necessary for fog formation Signup and view all the answers

What is the effect of temperature inversions on fog formation?

They suppress vertical mixing and allow fog to form Signup and view all the answers

What is the purpose of the autumn dust storm forecast process?

To forecast dust storms during a specific time period Signup and view all the answers

What is the role of subsidence inversions in fog formation?

They suppress vertical mixing and allow fog to form Signup and view all the answers

Why does fog formation occur under a surface anticyclone?

Because it holds water vapor at the surface and isolates the surface from the drier air aloft Signup and view all the answers

What is the main reason why dust is more difficult to detect at night in infrared imagery?

The land cools and the thermal contrast between the dust and land decreases Signup and view all the answers

What is the primary reason why dust is more easily detectable over the Red Sea in visible imagery?

The dark water background provides a high contrast to the dust Signup and view all the answers

What is the effect of forward scattering on dust detection in visible satellite imagery?

It increases the reflection of dust particles, making them more detectable Signup and view all the answers

Why is dust detection more difficult in visible imagery over land?

The dust blends in with the sandy land surface Signup and view all the answers

What is the primary difference between dust detection in visible and infrared imagery?

Visible imagery detects dust through reflection, while infrared imagery detects dust through temperature Signup and view all the answers

What is the primary reason why dust is more easily detectable in infrared imagery over land?

The dust is cooler than the underlying land surface Signup and view all the answers

What is the effect of backscattering on dust detection in visible satellite imagery?

It decreases the reflection of dust particles, making them less detectable Signup and view all the answers

Why does the dust plume shown in Figure 1.9 become more difficult to detect in the middle of the day?

Backscattering reduces the reflection of dust particles Signup and view all the answers

What type of clouds are characterized by transverse bands?

Billow clouds Signup and view all the answers

What is the typical range of visibility restricted by haze?

3 to 6 miles Signup and view all the answers

What is the purpose of the Stratospheric Layer Advanced Turbulence Index?

To forecast upper-level turbulence Signup and view all the answers

Where do elevated layers of haze occur?

both a and b Signup and view all the answers

What is the primary difference between rime icing and clear icing?

Rime icing is smooth, while clear icing is rough Signup and view all the answers

What is the typical height of the planetary boundary layer?

up to 2 km Signup and view all the answers

What is the primary factor contributing to the formation of front-passage fog in a low-latitude summer?

Evaporation of front-passage rain water cooling the surface and overlying air Signup and view all the answers

What is the typical location of cumuliform cloud icing?

Near warm fronts Signup and view all the answers

What is the primary cause of icing with a cold front?

Cold air from Canada Signup and view all the answers

What enhances oxidation reactions that form sulfate aerosols?

sunlight and/or liquid water Signup and view all the answers

What is the typical temperature range required for ice fog to form?

–20°C to –29°C (–4°F to –20°F) and colder Signup and view all the answers

What is the primary source of moisture that helps to produce ice fog?

Burning hydrocarbon fuels, steam vents, motor vehicle exhausts, and jet exhausts Signup and view all the answers

What is the typical atmospheric condition under which haze persists for days?

under persistent high pressure Signup and view all the answers

What is the purpose of the AFW-WEBS authoritative upper-level turbulence outlook?

To forecast upper-level turbulence Signup and view all the answers

What is the characteristic of sulfate aerosols?

they are hygroscopic Signup and view all the answers

What is the primary factor in determining the height to which a haboob can ascend?

Moisture content Signup and view all the answers

What is the term for the transition from solid directly to vapor?

Sublimation Signup and view all the answers

What is the characteristic shape of a billow cloud?

Transverse bands Signup and view all the answers

What is the typical condition under which ice crystals sublime?

Low humidity in below-freezing conditions Signup and view all the answers

What is the top of the planetary boundary layer (PBL) delineated by?

a temperature inversion and a cessation of vertical mixing Signup and view all the answers

What is the typical diameter of sulfate aerosols when humidity is low?

around a tenth of a micrometer Signup and view all the answers

What contributes to the persistence of ice fog?

A strong low-level inversion Signup and view all the answers

What is the typical time of day when sublimation fog occurs?

Sunrise Signup and view all the answers

What is the typical condition under which front-passage fog occurs?

Warm and cold air masses, each near saturation, being mixed by very light winds Signup and view all the answers

What is the primary characteristic that distinguishes a haboob from a dust devil?

Vertical extent of the cloud Signup and view all the answers

What is the primary factor that determines the height to which a haboob can ascend?

Vertical extent of the cumuliform cloud Signup and view all the answers

What is the typical duration of a haboob?

Up to an hour Signup and view all the answers

What is the primary effect of the precipitation that falls into the dry air in a desert environment?

It evaporates quickly Signup and view all the answers

What is the primary reason why the downdraft air spreads out in all directions in a haboob?

It is driven by the density difference between the downdraft air and the ambient air Signup and view all the answers

What is the typical shape of a dust devil once it is fully formed?

Conical Signup and view all the answers

What is the primary effect of the evaporation of precipitation on the air in a desert environment?

It cools the air Signup and view all the answers

What is the primary factor that determines the strength of a dust devil?

Wind speed at the surface Signup and view all the answers

What is the purpose of maintaining records as a result of processes prescribed in this publication?

To manage records in accordance with Air Force Manual 33-363 Signup and view all the answers

What is the main difference between the legacy 98/002 tech note and this Handbook?

The numerous techniques updated to reflect advanced processes Signup and view all the answers

What is the purpose of summarizing changes in the publication?

To completely review the document Signup and view all the answers

What is the primary purpose of using the Air Force Form 847?

To recommend changes of publication Signup and view all the answers

What is the result of not reviewing the document completely?

Missing updated techniques and procedures Signup and view all the answers

What is the primary reason for disposing of records in accordance with Air Force Records Information Management System Records Disposition Schedule?

To manage records efficiently Signup and view all the answers

What is the Office of Primary Responsibility responsible for?

Receiving recommendations for change of publication Signup and view all the answers

Why is it important to review the SUMMARY OF CHANGES section?

To stay updated on revised techniques and procedures Signup and view all the answers

Study Notes

Precipitation Types and Forecasting

Method 1 involves using a plot to identify areas where different precipitation types are expected to occur.
Table 1.7 shows the probability of snowfall as a function of freezing level height.
Figure 1.13 illustrates the relationship between melting layer depth and mean layer temperature for freezing rain potential.
Figure 1.14 depicts a typical freezing rain sounding, featuring the depth and magnitude of the melting layer and moisture into the dendritic layer.
Figure 1.15 presents a precipitation type nomogram based on 1000 mb and 850 mb wet bulb temperatures.
Figure 1.16 shows a precipitation type nomogram based on 1000-850 mb and 850-700 mb thicknesses.

Freezing Precipitation and Clouds

Figure 1.17 displays freezing drizzle soundings.
Figure 1.18 illustrates an idealized sleet sounding.
Figure 1.19 shows the relationship between MAXTEMP and SLR.

Clouds and Fog

Table 1.12 lists various types of clouds.
Figure 2.1 displays a WWMCA Cloud Free Plot over China and East Asia.
Figure 2.2 shows a global plot of mean total cloud amount, May, 1800-2100 UTC.
Figure 2.3 illustrates the calculation of the MCL.
Figure 2.4 depicts the CCL Parcel Method.
Table 2.1 lists the expected bases of convective clouds from surface dew point depression.
Figure 2.5 shows the stratus dissipation technique using mixing ratio and temperature.
Figure 2.6 illustrates the tropopause method of forecasting cirrus bases and tops.

Turbulence and Fog

Table 2.2 categorizes aircraft turbulence types.
Table 2.3 provides a turbulence conversion chart.
Figure 2.7 illustrates the Kelvin-Helmholtz wave lifecycle.
Table 2.4 explains the Richardson Number calculation and interpretation.
Figure 2.8 displays an "S-shaped" tropospheric temperature profile, indicating potential turbulence.
Figure 2.9 shows surface cyclogenesis and jet-core CAT and secondary jet-core CAT.
Frontal fog can be divided into three types: warm-front pre-frontal fog, cold-front post-frontal fog, and front-passage fog.
Ice fog forms in extremely cold, arctic air (–29°C (–20°F) and colder) and is composed of ice crystals rather than water droplets.
Sublimation fog occurs when ground frost sublimes at sunrise, increasing atmospheric moisture.

Dust Storms and Visibility

Convective dust storms are difficult to forecast and are typically a small-scale phenomenon.
Dust devils occur when strong surface heating under clear skies and light winds warms the air near the ground to temperatures well above those just above the surface layer.
Haboobs are intense dust events that can propagate in the direction of the average cloud-bearing layer winds and can travel up to 60-90 miles.
Peak winds in the haboob are approximately 95% greater than the speed of movement.
Duration of haboobs can vary, but can reach up to six hours.

Visibility Forecasting Aids and Techniques

AFW Ensemble Visibility Forecasts use statistical regression analyses of relative humidity, precipitable water, and surface wind speed to produce visibility probability products.
Visibility climatology is an important tool for forecasting visibility.

Visibility Restrictions

Post-frontal fog is associated with slow-moving cold fronts
Visibility limits are affected by snowfall intensity, with higher intensities resulting in lower visibility
Dust-lofting wind speeds vary by desert environment, with higher speeds required in certain environments

Fog Formation

Fog threat thresholds indicate the likelihood of radiation fog formation
Fog Stability Index (FSI) thresholds also indicate the likelihood of radiation fog formation
Radiation fog point is calculated by following an isohume down to the surface from the dew point at the LCL

Dust Detection

Infrared imagery is less useful at night due to decreased contrast between dust and land
Visible imagery is more effective during the day, with dust standing out over dark water backgrounds
Dust detection varies at sunrise and sunset due to forward scattering and backscattering

Radiosonde and Satellite Imagery

Radiosonde data can be used to calculate the radiation fog point and Fog Stability Index
Satellite imagery can be used to detect dust, with infrared imagery being more effective over land
Autumn dust storm forecast process involves determining the mission scenario, examining thunderstorm and blowing dust climatology, and analyzing the synoptic environment

Fog Formation

Fog forms when moist air cools to its dew point, and the air becomes saturated
A wet surface, such as water or moist vegetation, serves as a source of moisture for the planetary boundary layer (PBL), increasing the dew point and reducing the amount of cooling required for fog formation
Surface winds less than 10 knots are necessary for fog formation, as stronger winds make it difficult for saturation to be achieved by maintaining a well-mixed PBL and bringing in drier ambient air

Advection Fog

Advection fog forms when moist air is blown over a cooler surface, causing the air to cool to its dew point
Moisture convergence is important for advection fog formation, especially along coastlines or in areas of complex terrain
Precipitation falling into a slightly unsaturated layer can bring surface relative humidity to 100%, leading to fog formation
Advection fog is relatively shallow and accompanied by a surface-based inversion
The depth of advection fog increases with increasing wind speed, but wind speeds above 9 knots can cause the fog to lift into a low stratus cloud deck

Radiation Fog

Radiation fog forms when the air is cooled to its dew point through radiative cooling of the earth's surface
Dry air above the surface is necessary for radiation fog development and evolution
Dry air above the surface to great heights aloft is indicative of clear skies conducive to radiative cooling
The presence of dry air aloft allows the top of the fog deck to continue to cool, reinforcing the fog and often causing it to intensify

Sea Fog

Sea fog forms when warm, moist air is cooled to saturation as it moves over cold water
If the initial dew point is less than the coldest water temperature, sea fog formation is unlikely
Sea fog dissipates if a change in wind direction carries the fog over a warmer surface

Dust Devils and Haboobs

Dust devils are small, rotating columns of air that form when the ground is heated by the sun
Dust devils are typically smaller and less intense than tornadoes, but can achieve the intensity of a weak tornado
Haboobs are intense dust storms generated by the convective outflow from a collapsing or ongoing thunderstorm, or from any collapsing cumuliform cloud of appreciable vertical extent
Haboobs are most frequent in desert environments, where low-level air is very dry and any precipitation will quickly evaporate, cooling the ambient air and making it negatively buoyant with a tendency to sink towards the surface

Meteorological Techniques

The Air Force Handbook 15-101 provides general guidance for effective meteorological techniques for various parameters.

Visibility Obstructions

Haze particles produce a bluish color when viewed against a dark background and yellowish when viewed against a lighter background due to Mie scattering.
Haze occurs under a stable atmospheric layer and significantly affects visibility.
Industrial areas and coastal areas are most conducive to haze formation.

Smoke

Smoke is usually more localized than other visibility restrictions.
Accurate visibility forecasts depend on detailed knowledge of local terrain, surface wind patterns, and smoke sources.

Blowing Dust and Sand

Windblown particles such as blowing dust and sand can cause serious local restrictions to visibility.
The critical wind speed for lifting dust and sand varies according to vegetation, soil type, and soil moisture.
Specific forecasting rules vary by station and time of year.

Moist Obstructions (Hydrometeors)

Condensation or sublimation of atmospheric water vapor produces a hydrometeor.
Hydrometeors that cause surface visibility reductions generally fall into two categories: precipitation and fog.

Dust Storms

Favorable parameters for dust storm generation include:
- Unstable boundary layers
- Strong radiative cooling
- Low humidity
- Wind speeds above 15 mph
Threshold dust-lofting wind speeds vary depending on the environment (e.g. 10-15 mph in dune-covered areas, 20-25 mph in sandy areas).
Summer shamal dust storms can extend up to 15,000-18,000 feet tall and last for 1-10 days.

Climatology

The 14th Weather Squadron is the Air Force's climatology center.
Useful products for fog forecasting include:
- Wind stratified conditional climatologies (WSCC)
- Surface climograms
- Operational climatic data summaries (OCDS-II)
WSCC indicate the percentage likelihood of a particular visibility category given a set of initial conditions.
Surface climograms show the likelihood of an event's occurrence (e.g. fog).
OCDS-II enables users to generate plots of fog frequency, stratified by time of day and month of the year.

Atmospheric Heating and Cooling

Atmospheric heating and cooling occur through radiation gains and losses under clear skies.
Figure 1.28 illustrates the standard surface model of daily atmospheric heating and cooling.

Computation of Maximum Skew-T Temperature

Maximum Skew-T temperature can be computed with or without inversion, and under mostly cloudy or mostly clear skies.
Figure 1.29 shows the computation of maximum Skew-T temperature in different scenarios.

Pressure

Pressure is an important factor in atmospheric science.
Tables 1.21 and 1.22 provide standard atmospheric pressure and temperature values at different altitudes and levels.
Table 1.23 lists altimeter settings.
Figures 1.30 and 1.31 illustrate pressure conversion charts and pressure altitude formulas.

Flight Weather Elements

Fog formation requires a source of moisture, such as a wet surface or vegetation.
A wet surface is especially important for radiation fog formation.
Surface winds less than 10 knots are favorable for fog formation, as they maintain a well-mixed planetary boundary layer and bring in moist air.
Dry air with a relative humidity less than 50% above the surface is important for radiation fog development and evolution.

Fog Formation

Advection fog is characterized by stronger surface winds than radiation fog.
Surface winds greater than 10 knots are detrimental to fog formation, as they make it difficult for saturation to be achieved.
Dry air above the surface allows the top of the fog deck to continue to cool via outgoing IR radiation, which reinforces the fog deck and often causes it to intensify.

Dust Removal Mechanisms

Lofted dust eventually settles, but may travel halfway around the globe before doing so.
The three most common dust removal mechanisms are dispersion, advection, and entrainment in precipitation.
Dispersion is primarily influenced by turbulence, which mixes ambient air with the dust plume.

Radiation Fog Point

The radiation fog point is calculated by following an isohume (line of constant saturation mixing ratio) down to the surface from the dew point at the LCL.
Figure 1.7 illustrates the radiation fog point calculation.

Radiation Fog Threat

The radiation fog threat indicates the potential for radiation fog formation and is calculated by subtracting the radiation fog point from the 850 mb wet-bulb potential temperature (WBPT850).
Table 1.4 provides fog threat thresholds, indicating the likelihood of radiation fog formation.

Radiation Fog Stability Index

The radiation fog stability index uses a representative 1200Z sounding to give the likelihood of radiation fog formation.
Table 1.5 lists fog stability index (FSI) thresholds, indicating the likelihood of radiation fog formation.
FSI is defined as: FSI = 4TSfc - 2(T850 + TdSfc) + W850
FSI is indicative of radiation fog potential if there is strong static stability between the surface and 850 mb, ample moisture in the layer, and slow wind speeds at 850 mb.

Visibility Forecasting Aids and Techniques – Dust

AFW Ensemble blowing dust forecasts provide blowing dust probability products for visibilities less than five, three, and one statute miles.
Satellite detection of dust is difficult, especially at night and in single channel imagery.
Enhanced RGB satellite imagery and Aerosol Optical Depth (AOD) can help identify dust, and satellite animations can track dust over land during the day.

Turbulence in a Deformation Zone

Figures 2.23-2.26 illustrate various types of turbulence, including transverse bands, billow clouds, mountain waves, and authoritative upper-level turbulence outlook

Icing

Rime icing and clear icing (smooth and rough varieties) are types of icing that occur under different temperature conditions (Figures 2.27-2.28)
Icing type and amount can be determined by temperature (Tables 2.10-2.11)
Cumuliform cloud icing locations and icing with warm and cold fronts are illustrated in Figures 2.29-2.31

Fog

Fog forms when the temperature and dew point of the air approach the same value, either through cooling of the air or by adding moisture (Figure 2.32)
Advection fog forms due to moist air moving over a colder surface, while radiation fog is produced by radiational cooling
Upslope fog occurs when sloping terrain lifts air, cooling it adiabatically to its dew point and saturation
Frontal fog forms when a wet surface serves as a source of moisture for the planetary boundary layer

Features of Fog

Surface winds less than 10 knots are conducive to fog formation
Dry air with relative humidity less than 50% above the surface moist layer is important for radiation fog development

Dust Detection

Daytime detection of dust is easier than at night due to differences in visible and infrared imagery
Forward scattering of dust particles enhances reflection at sunrise and sunset, making detection easier
Aerosol Optical Depth (AOD) measures the amount of light prevented from passing through the atmosphere by airborne particles
Surface climograms provide a two-dimensional view of the likelihood of reduced visibility due to dust

Forecasting Haboobs

Haboobs can be forecast by determining elevated instability, high mid-level moisture, and steep lapse rates
Forecasting haboobs from collapsing thunderstorms involves finding the cloud base height of the thunderstorm and determining haboob potential after sunset

Precipitation

Precipitation refers to all forms of water particles, both liquid and solid, that fall from the atmosphere and reach the ground
Types of precipitation include:
- Liquid precipitation (drizzle and rain)
- Freezing precipitation (freezing drizzle and freezing rain)
- Solid (frozen) precipitation (ice pellets, hail, snow, snow pellets, snow grains, and ice crystals)

Suspended Water Particles

Suspended water particles that form and remain in the air can cause restrictions to visibility
Types of suspended water particles include:
- Damp haze
- Cloud
- Fog
- Ice fog
- Mist
Suspended water particles can also be lifted by the wind from the earth's surface, including:
- Drifting snow
- Blowing snow
- Blowing spray

Whiteout Conditions

Whiteout is a visibility-restricting phenomenon that occurs when a uniformly overcast layer of clouds overlies a snow- or ice-covered surface
Whiteout occurs when the cloud deck is relatively low and the sun angle is at about 20° above the horizon
Cloud layers break up and diffuse parallel rays from the sun, causing light to reflect back and forth between the snow and clouds
This eliminates shadows and makes it difficult to distinguish the boundary between the ground and the sky

Fog

Fog forms when the air becomes supersaturated with water vapor, allowing visible cloud droplets to form
Mixed-phase (freezing) fogs and ice fogs can develop even if the environment is slightly unsaturated with respect to liquid water
RH with respect to water is typically between 99% and 99.9% for fog formation
RH with respect to ice may or may not be greater than 100% for fog formation
Fog can form through various mechanisms, including:
- Temperature cooling to the dew point via cold air advection or radiational cooling
- Dew point increasing to the temperature via moisture advection or evapotranspiration from the earth's surface
- Precipitation rapidly raising the dew point and cooling the temperature
- Introduction of more fine particulates into the air, allowing supersaturation to be achieved

Snow and Blowing Snow

Blowing snow is snow that is lifted from the surface of the earth by the wind to a height of 2 meters or more, and is blown about in such quantities that horizontal visibility is reduced to less than 7 statute miles
Snow can be falling snow or snow that has already accumulated but is picked up by strong winds
Forecasting visibility in snow or blowing snow involves considering factors such as wind speed, snowfall rate, and snow cover
Rules of thumb for forecasting visibility in snow or blowing snow include:
- Moderate, dry, and fluffy snowfall with wind speeds exceeding 15 knots usually reduces visibility
- Snow cover that has previously been subject to wind movement does not produce as severe a visibility restriction as new snow
- Snow cover that fell when temperatures were near freezing does not blow except in very strong winds
- The stronger the wind, the lower the visibility in blowing snow
- Loose snow becomes blowing snow at wind speeds of 10 to 15 knots or greater

Dust Storms

Dust storms are a function of wind speed, wind direction, and soil moisture content
Forecasting dust generation is more difficult than forecasting the advection of observed dust into the area
Key factors to consider in forecasting dust storms include:
- Common dust source regions, including deserts, agricultural areas, and coastal areas
- Wind speed and direction
- Soil moisture content
- Synoptic situations, such as cold frontal passages, that can change wind direction and probability of dust advection

Climatological Data

The 14th Weather Squadron operates and maintains a vast library of climatological data
Useful products for fog forecasting include:
- Wind stratified conditional climatologies (WSCC)
- Surface climograms
- Operational climatic data summaries (OCDS-II)
WSCCs provide the percentage likelihood that a particular visibility category will be observed at a future hour
Surface climograms show the likelihood of an event's occurrence, including fog
OCDS-II enables users to generate plots of fog frequency, stratified by time of day and month of the year

Surface Weather Elements

Visibility is defined as the greatest distance in a given direction at which it is just possible to see and identify with the unaided eye, a prominent dark object against the sky at the horizon, or at night, a known, preferably unfocused, moderately intense light source.

Dry Obstructions (Lithometeors)

Lithometeors are particles suspended in a dry atmosphere, including haze, smoke, dust, and sand.
Haze is an accumulation of very fine dust or salt particles in the atmosphere; it does not block light, but instead causes light rays to scatter.

Advection Fog

Advection fog is relatively shallow and accompanied by a surface-based inversion.
The depth of advection fog increases with increasing wind speed, but at wind speeds above 9 knots, greater turbulent mixing usually causes advection fog to lift into a low stratus cloud deck.
Favorable conditions for advection fog include:
- Coastal areas where moist air is advected over water cooled by upwelling.
- In winter, when warm, moist air flows over colder land.
- Warm, moist air that is cooled to saturation as it moves over cold water, forming sea fog.

Haze Formation

Sulfate aerosols are formed when sulfur dioxide released from industry bonds with oxygen in oxidation reactions enhanced by sunlight and/or liquid water.
Sulfate aerosols are hygroscopic, making them effective condensation nuclei, and can grow large enough to be seen as clouds when the environment is supersaturated.
When the humidity is low, sulfate aerosols only grow to around a tenth of a micrometer in diameter and remain suspended in the atmosphere to form haze.

Haze Characteristics

Haze usually occurs in the planetary boundary layer (PBL), which extends from the surface up to about 2 km on average, but can extend up to 500 mb in places like Southwest Asia.
Elevated layers of haze can also occur, such as in regions downstream from where particles have been lofted above the PBL by cumulus clouds.
Haze can persist for days in the absence of a cleansing mechanism such as precipitation, especially when atmospheric conditions are stagnant, such as under a persistent area of high pressure.

Dust Storms

Frontal dust storms are caused by synoptic-scale systems whose winds carry sand particles over large distances.
The three major varieties of frontal dust storms are prefrontal, postfrontal, and shear-line.
Prefrontal dust storms occur across much of SWA as low pressure systems move across the region, with winds called the Sharqi in Iraq, the Kaus in Saudi Arabia, the Shlour in Syria and Lebanon, and the Khamsin in Egypt.

Meteorological Techniques

The Air Force Handbook 15-101 is a formal publication that provides general guidance for effective meteorological techniques for various parameters.
The handbook is derived from the legacy Field Operating Agency Technical Note 98/002, Meteorological Techniques, and supersedes all existing iterations of the legacy document.

Dust Storms

River flood plains, such as the Tigris and Euphrates Rivers in southern Iraq, can serve as the source region for many dust storms, particularly during shamal events.
Shamals are strong northwesterly winds that blow over Iraq and the Persian Gulf states, often decreasing in strength at night.
Dry lake beds can also be a source of dust storms, as the fine-grained soils formed by eroded rocks can inhibit plant growth and blow easily in strong winds.

Dust Lofting Mechanisms

Wind from the surface through the depth of the boundary layer is necessary to move and loft dust particles.
Table 1.2 shows threshold dust-lofting wind speeds for different desert environments, ranging from 10 to 25 knots.
The first sand and dust particles to move are those from 0.08 to 1 mm in diameter, which occurs with wind speeds of 10 to 25 knots.
Winds at the surface need to be 15 knots or greater to mobilize dust.
Once a dust storm starts, it can maintain the same intensity even when wind speeds slow to below initiation levels, since the bond between dust particles and the surface is already broken.
Lofting of dust also requires turbulence in the boundary layer, which can be created by wind shear.

Frontal Dust Storms

Frontal dust storms are caused by synoptic-scale systems whose winds carry sand particles over large distances.
The three major varieties of frontal dust storms are prefrontal, postfrontal, and shear-line.
Prefrontal dust storms occur across much of SWA as low pressure systems move across the region.
Prefrontal winds are called the Sharqi in Iraq, the Kaus in Saudi Arabia, the Shlour in Syria and Lebanon, and the Khamsin in Egypt.

Fog Forecasting

The 14th Weather Squadron operates and maintains a vast library of climatological data, including wind stratified conditional climatologies (WSCC), surface climograms, and operational climatic data summaries (OCDS-II).
WSCC indicate the percentage likelihood that a particular visibility category will be observed at a future hour, given a set of initial conditions.
Surface climograms are two-dimensional views of the likelihood of an event's occurrence, including fog.
OCDS-II enables users to generate plots of fog frequency, stratified by time of day and month of the year, for a user-selected station.

Radiation Fog Point

The radiation fog point is the temperature (in °C) at which radiation fog forms.
To find the FP, first find the pressure level of the LCL.

Aerosol Optical Depth (AOD)

AOD is a unit-less measure of the amount of light that airborne particles, such as dust, smoke, haze, and pollution, prevent from passing through a column of the atmosphere.
AOD doesn't provide surface visibility estimates, but it can serve as a first-order indicator of potential reduced surface visibilities.

Haboob Forecasting

Forecasting haboobs from ongoing thunderstorms requires determining if elevated instability is present, looking for high mid-level moisture and steep lapse rates, and finding the strongest wind at any level aloft where the wet bulb potential temperature is less than the surface potential temperature by at least 4°C.
Forecasting haboobs from collapsing thunderstorms requires determining haboob potential after sunset, when buoyancy diminishes, and finding the cloud base height of the thunderstorm.

Thunderstorms

Types of thunderstorms: single cell, multi-cell, and supercell
Supercell characteristics: strong updrafts, strong downdrafts, and a rotating updraft known as a mesocyclone
Classic supercell: strong updrafts, strong downdrafts, and a rotating updraft
High-precipitation supercell: strong updrafts, strong downdrafts, and a large amount of precipitation
Low-precipitation supercell: strong updrafts, weak downdrafts, and a small amount of precipitation
Microburst atmospheric profiles: dry, wet, and hybrid

Synoptic Patterns

Severe thunderstorm development potential: dependent on wind shear, instability, and moisture
Type A severe weather synoptic pattern: dryline
Type B severe weather synoptic pattern: frontal
Type C severe weather synoptic pattern: overrunning
Type D severe weather synoptic pattern: cold core
Type E severe weather synoptic pattern: squall line

Fog

Types of fog: radiation, advection, steam, and ice fog
Ice fog: composed of ice crystals, forms in extremely cold air (–29°C or –20°F), and persists until temperature rises or air mass changes
Sublimation fog: occurs when ground frost sublimes at sunrise, increasing atmospheric moisture
Moisture convergence: occurs along coastlines, in complex terrain, and frontal boundaries, and is a key factor in advection fog formation
Precipitation fog: occurs when precipitation falls into a slightly unsaturated layer, bringing surface relative humidity to 100% or slight supersaturation

Radiation Fog

Occurs in air with a high dew point, ensuring radiation cooling lowers the air temperature to the dew point
Factors influencing radiation fog forecast: nighttime minimum temperature, air near the ground becoming saturated, calm conditions, and constant or increasing dew points with height
Stable air mass with cloud cover during the day, clear skies at night, light winds, and moist air near the surface are conducive to radiation fog formation

Dust Storms

Favorable conditions for dust storm generation: strong winds, dry air, and loose soil or sand
Threshold dust-lofting wind speeds for different desert environments:
- Fine to medium sand in dune-covered areas: 10 to 15 mph (8.7 to 13 knots)
- Sandy areas with poorly developed desert pavement: 20 mph (17.4 knots)
- Fine material, desert flats: 20 to 25 mph (17.4 to 21.7 knots)
- Alluvial fans and crusted salt flats (dry lake beds): 30 to 35 mph (26.1 to 30.4 knots)
- Well-developed desert pavement: 40 mph (36.8 knots)
Diurnal effects: strong radiative cooling leads to rapid heat loss after sunset, resulting in a surface-based inversion, which may inhibit dust lofting

Document Information

The document is substantially revised and should be completely reviewed.
It is based on the 2012 tech note revision.
Numerous techniques were updated to reflect advanced processes and procedures.
Many illustrations and figures were modernized with improved graphics and pictures.

Surface Weather Elements

Visibility limits are based on snowfall intensity.
Table 1.1 provides visibility limits based on snowfall intensity.
Figure 1.2 shows pre-frontal fog associated with a warm front.
Figure 1.3 shows post-frontal fog associated with a slow-moving cold front.
Table 1.2 provides threshold dust-lofting wind speeds for different desert environments.
Table 1.3 shows favorable conditions for the generation and advection of dust.

Visibility

Figure 1.4 shows a WSCC example.
Figure 1.5 shows a visibility climogram example for Vandenberg AFB.
Figure 1.6 shows an OCDS-II example.
Figure 1.7 shows a radiation fog point example.
Table 1.4 provides fog threat thresholds, indicating likelihood of radiation fog formation.
Table 1.5 provides fog stability index (FSI) thresholds, indicating likelihood of radiation fog formation.

Precipitation

Figure 1.11 shows overrunning associated with a typical cyclone.
Figure 1.12 shows clouds.

Clouds

Figure 2.1 shows a WWMCA cloud-free plot over China and East Asia.
Figure 2.2 shows a global plot of mean total cloud amount, May, 1800-2100 UTC.
Figure 2.3 shows the calculation of the MCL.
Figure 2.4 shows the CCL parcel method.
Table 2.1 provides expected bases of convective clouds from surface dew point depression.

Turbulence

Table 2.2 provides aircraft turbulence category type.
Table 2.3 provides turbulence conversion chart.
Figure 2.7 shows Kelvin-Helmholtz wave lifecycle.
Table 2.4 provides Richardson number calculation and interpretation.
Figure 2.8 shows an "S-shaped" tropospheric temperature profile, indicating potential turbulence.
Figure 2.9 shows surface cyclogenesis and jet-core CAT and secondary jet-core CAT.
Figure 2.10 shows CAT during the development of an upper-level low.
Figure 2.11 shows CAT area along a shear line associated with an upper-level low.
Figure 2.12 shows CAT in a diffluent wind pattern.
Figure 2.13 shows CAT areas in shearing troughs.
Figure 2.14 shows CAT with wind maximum to the rear of the upper trough.
Figure 2.15 shows CAT with upper-level ridges.
Figure 2.16 shows mountain wave cloud structure.
Table 2.5 provides low-level mountain wave turbulence guidance chart.
Figure 2.17 shows a mountain wave turbulence nomogram.
Figure 2.18 shows gravity waves on visible satellite imagery.
Table 2.6 provides expected turbulence locations.
Figure 2.19 shows a low-level turbulence forecasting flowchart for category II aircraft.
Figure 2.20 shows convective cloud turbulence forecasting using the Skew-T.
Table 2.7 provides surface-9000 foot temperature difference vs. turbulence intensity.
Table 2.8 provides layer above 9000 feet temperature difference vs. turbulence intensity.
Figure 2.21 shows a low-level turbulence nomogram.

Dust Storms

Dust storms are a function of wind speed, wind direction, and soil moisture content.
Wind speed becomes important in advection of the dust after generating blowing dust upstream.
Duration of the advected dust is a function of the depth of the dust and the advecting wind speeds.

Dust Source Regions

Deserts: dust storms occur in regions with little vegetation and precipitation.
Agricultural areas: fallow, recently tilled, or marginal growing climate areas are potential sources of dust.
Coastal areas: dust plumes can be generated in advance of cold fronts moving across sandy or silty coastal regions.

Frontal Dust Storms

Caused by synoptic-scale systems whose winds carry sand particles over large distances.
Accompany low-pressure systems and associated frontal boundaries.
Three major varieties: prefrontal, postfrontal, and shear-line.

Prefrontal Dust Storms

Occur across much of SWA as low-pressure systems move across the region.
Prefrontal winds are called the Sharqi in Iraq, the Kaus in Saudi Arabia, the Shlour in Syria and Lebanon, and the Khamsin in Egypt.
Easterly to southerly prefrontal winds are favored for prefrontal dust storms in October and November.

Haboobs

Intense dust storms generated by the convective outflow from a collapsing or ongoing thunderstorm.
Most frequent in the deserts of northern Africa, but also occur in SWA and the southwestern United States.
Cooldown of the ambient air by precipitation makes it negatively buoyant, causing it to sink towards the surface.

Radiation Fog Threat (FT)

Indicates the potential for radiation fog formation.
Calculated by subtracting the radiation fog point from the 850 mb wet-bulb potential temperature (WBPT850).
Table 1.4 provides the likelihood of radiation fog formation based on the fog threat value.

Radiation Fog Stability Index (FSI)

Uses a representative 1200Z sounding to give the likelihood of radiation fog formation.
Defined in Table 1.5, which provides the likelihood of radiation fog formation based on the FSI value.
FSI is indicative of radiation fog potential if there is strong static stability between the surface and 850 mb, ample moisture in the layer, and slow wind speeds at 850 mb.

Visibility Forecasting Aids and Techniques – Dust

AFW Ensemble blowing dust forecasts: GEPS and MEPS produce blowing dust probability products for visibilities less than five, three, and one statute miles.
Satellite detection of dust: satellite animations (especially daytime visible imagery) can help identify the location of dust, and Aerosol Optical Depth (AOD) has somewhat eased difficulties in detecting dust.

Clouds

Figure 2.1 shows a cloud-free plot over China and East Asia
Figure 2.2 displays a global plot of mean total cloud amount from 1800-2100 UTC
Figure 2.3 illustrates the calculation of the MCL (Mean Cloud Layer)
Figure 2.4 shows the CCL Parcel Method

Turbulence

Table 2.2 outlines the aircraft turbulence category type
Table 2.3 provides a turbulence conversion chart
Figure 2.7 shows the Kelvin-Helmholtz wave lifecycle
Table 2.4 explains the Richardson Number calculation and interpretation
Figure 2.8 displays an "S-shaped" tropospheric temperature profile, indicating potential turbulence

Intake Icing

Figure 2.33 shows carburetor icing
Figure 2.34 displays carburetor icing potential
Table 2.12 outlines icing potential based on temperature and dew point depression
Figure 2.35 illustrates typical icing areas in a mature cyclone
Figure 2.36 provides an icing flowchart
Figure 2.37 shows the "-8D Method" for determining icing potential

Miscellaneous Weather Elements

Figure 2.38 shows increasing flight level winds with CAA (Cold Air Advection)
Figure 2.39 displays decreasing flight level winds with WAA (Warm Air Advection)
Figure 2.40 illustrates contrail formation
Figure 2.41 provides an Appleman chart for contrail forecasting
Figure 2.42 shows Appleman charts for non-bypass, low-bypass, and high-bypass engines
Table 2.13 outlines engine bypass type for military aircraft
Figure 2.43 displays the GALWEM no-bypass forecast product

Blowing Snow

Blowing snow is a greater hazard to flying operations in polar regions than in mid-latitudes
Fresh snow blows or drifts at temperatures of -20°C (-4°F) or less
After 3 or more days of exposure to direct sunlight, snow forms a crust and does not readily drift or blow
The crust is seldom uniform across a snowfield, and terrain undulations, shadows, and vegetation often retard the formation of the crust
If additional snow falls onto snowpack that has already crusted, only the new snow blows or drifts

Haze and Dust

Research shows that the primary constituent of haze droplets over industrial areas is sulfuric acid
Prefrontal dust storms can be difficult to detect in METSAT imagery
Postfrontal dust storms are associated with a dynamic weather feature (e.g., cold front)
Postfrontal dust storms typically reach 8,000-15,000 feet, but can reach up to jet stream level (~30,000 feet)
Surface winds are 15-30 knots on average, but gusts of 40-50 knots may occur with very strong low-pressure systems
Wind speed can be estimated by the thermal contrast across the front
There are two types of postfrontal dust storms: one lasting 24-36 hours, and another lasting 3-5 days
Dust devils are typically smaller and less intense than tornadoes, with a diameter of 10-300 feet and an average height of 500-1000 feet
Dust devils typically last only a few minutes, but may persist for up to an hour in optimal conditions
A haboob is an intense dust storm generated by the convective outflow from a collapsing or ongoing thunderstorm, or from any collapsing cumuliform cloud of appreciable vertical extent

Surface Winds

Centrifugal and centripetal forces contribute to the formation of surface winds
Geostrophic wind and isallobaric wind are two types of surface winds

Visibility Restrictions

Haze particles produce a bluish color when viewed against a dark background and a yellowish color when viewed against a lighter background
Haze occurs under a stable atmospheric layer and significantly affects visibility
Industrial areas and coastal areas are most conducive to haze formation
Smoke is usually more localized than other visibility restrictions
Accurate visibility forecasts depend on detailed knowledge of the local terrain, surface wind patterns, and smoke sources
Blowing dust and sand can cause serious local restrictions to visibility, often reducing visibility to near zero
The critical wind speed for lifting dust and sand varies according to vegetation, soil type, and soil moisture

Moist Obstructions (Hydrometeors)

Condensation or sublimation of atmospheric water vapor produces a hydrometeor
Hydrometeors that cause surface visibility reductions generally fall into two categories: precipitation and fog
Precipitation wouldn't be possible if the air was perfectly pure with no particulates
Mixed-phase (freezing) fogs and ice fogs can develop even if the environment is slightly unsaturated with respect to liquid water
RH with respect to water will typically be between 99% and 99.9%, while RH with respect to ice may or may not be greater than 100%

Fog Formation

The surface air can become saturated via several mechanisms:
- Temperature cooling to the dew point via cold air advection or radiational cooling
- Dew point increasing to the temperature via moisture advection or evapotranspiration from the earth's surface
- Precipitation very rapidly raises the dew point and cools the temperature so they eventually equal each other
- Introduction of more fine particulates (ash, dust, etc.) into surface air that is already very moist

Dust Storms

Dust storms can be classified into several types: shamal, frontal, and convective
The shamal is unique to the Middle East, but frontal and convective dust storms can be experienced in other arid regions
Shamal dust storms are caused by prevailing north winds over the Arabian Peninsula, Iraq, and Kuwait
Prefrontal dust storms can be difficult to detect in METSAT imagery because they are short-lived and often located over similarly shaded terrain
Postfrontal dust storms are associated with a dynamic weather feature (e.g., cold front) and can reach greater heights than those associated with shamal winds

Atmospheric Heating and Cooling

Figure 1.28 illustrates the standard surface model of daily atmospheric heating and cooling in relation to radiation gains and losses under clear skies.

Temperature

Maximum Skew-T temperature can be computed with or without inversion, and with mostly cloudy or mostly clear skies (Figure 1.29).
K-value correction factors are provided for the Callen and Prescott method (Table 1.18) and the McKenzie method (Table 1.19).
Wind chill temperature chart is provided in Table 1.20.

Pressure

Standard atmospheric pressure and temperature are given by altitude (Table 1.21) and by level (Table 1.22).
Altimeter settings are provided in Table 1.23.
A pressure conversion chart is given in Figure 1.30.
The pressure altitude formula is shown in Figure 1.31.

Flight Weather Elements

Intake icing can occur in certain conditions, and can be predicted using the carburetor icing potential chart (Figure 2.33) and the icing potential table (Table 2.12).
Icing areas can be identified in a mature cyclone (Figure 2.35).
Icing flowcharts are provided to help with icing prediction (Figure 2.36).
The "-8D Method" can be used to determine icing potential (Figure 2.37).

Miscellaneous Weather Elements

Increasing flight level winds with CAA (cold air advection) are illustrated in Figure 2.38.
Decreasing flight level winds with WAA (warm air advection) are illustrated in Figure 2.39.
Contrail formation can be predicted using the Appleman chart (Figure 2.41) and the GALWEM forecast product (Figure 2.43).
Engine bypass type is important for contrail formation (Table 2.13).

Fog

Fog can form when light precipitation falls into an unsaturated layer of air, cooling and moistening the air.
Warm air advection (WAA) can strengthen a temperature inversion, leading to longer fog duration.
Stability is important for fog formation, with fog rarely forming in a statically or conditionally unstable PBL.
Surface dew points are important for fog formation, with high surface dew points generally meaning that the surface will not need to cool as much to achieve saturation.

Dust

Dust can be detected in visible and infrared satellite imagery, with different detection capabilities during the day and at night (Figures 1.8 and 1.9).
Dust detection is affected by the time of day, with forward scattering occurring at sunrise and sunset.
The autumn dust storm forecast process involves determining the mission scenario, examining thunderstorm and blowing dust climatology, and analyzing the synoptic environment.

Office of Primary Responsibility

Refer recommended changes and questions about this publication to the Office of Primary Responsibility listed above using the Air Force Form 847
Route AF Forms 847 from the field through the appropriate chain of command

Record Management

Maintain all records created as a result of processes prescribed in this publication in accordance with Air Force Manual 33-363, Management of Records
Dispose of records in accordance with Air Force Records Information Management System Records Disposition Schedule

Summary of Changes

The document has been substantially revised and should be completely reviewed
The legacy 98/002 tech note has been updated several times over the twenty years since its initial publication
This Handbook was created based upon the 2012 tech note revision as a starting point
Numerous techniques were updated to reflect advanced processes and procedures
Many illustrations and figures were modernized with improved graphics and pictures

Surface Weather Elements

Visibility can be affected by various weather conditions
Whiteout conditions can occur
Pre-frontal fog associated with a warm front can occur
Turbulence in a deformation zone can occur
Transverse bands can occur
Billow clouds can occur
Mountain waves can occur
AFW-WEBS authoritative upper level turbulence outlook can be used
Stratospheric Layer Advanced Turbulence Index can be used to measure turbulence

Icing

Rime icing can occur
Clear icing can occur in smooth and rough varieties
Icing type is based on temperature
Icing amounts can be defined
Cumuliform cloud icing locations can occur
Icing can occur with a warm front
Icing can occur with a cold front

Fog

Fog can be caused by rain falling into cold stable air and raising the dew point
Frontal-passage fog can occur in a number of situations
Ice fog is composed of ice crystals rather than water droplets and forms in extremely cold, arctic air
Sublimation fog occurs when ground frost sublimes at sunrise, increasing atmospheric moisture
Sublimation fog can occur in areas with sulfur dioxide pollution

Haze

Haze can occur in the planetary boundary layer (PBL)
The top of the PBL is delineated by a temperature inversion and a cessation of vertical mixing
Sulfate aerosols are hygroscopic and can form haze
Haze can persist for days in stagnant atmospheric conditions
Elevated layers of haze can occur

Dust Devils and Haboobs

Dust devils are typically smaller and less intense than tornadoes
Dust devils can achieve the intensity of a weak tornado
Dust devil diameter is typically between 10 and 300 feet
Dust devils typically last only a few minutes, but may persist for up to an hour
Haboobs are intense dust storms generated by the convective outflow from a collapsing or ongoing thunderstorm
Haboobs are most frequent in the deserts of northern Africa, but they also occur in SWA and the southwestern United States

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Questions and Answers

What is the primary purpose of the precipitation type nomogram shown in Figure 1.15?

Which of the following is NOT a factor in determining the potential for freezing rain?

What is the primary difference between the two precipitation type nomograms shown in Figures 1.15 and 1.16?

What is the main purpose of Figure 1.17?

According to Table 1.8, what is the relationship between snowfall accumulation and surface visibility?

What is the primary purpose of Tables 1.9-1.11?

Which of the following is a key factor in determining the potential for sleet?

What is the main purpose of Figure 1.14?

What is the primary cause of pre- and post-frontal fog?

What is the minimum temperature required for ice fog to form?

What is the primary source of water vapor and pollutants that help to produce ice fog?

What is the term for the transition from solid directly to vapor?

What is the typical condition under which ice crystals sublime?

What contributes to the persistence of ice fog?

What is the typical time of day when sublimation fog occurs?

What is the typical condition under which front-passage fog occurs?

What is the main reason for the formation of dust storms in winter along the Arabian Peninsula, Red Sea, and equatorial regions of Africa?

What is the typical wind speed range during dust storms in the Arabian Sea?

What is the primary characteristic of convective dust storms that makes them difficult to forecast?

What is the role of hot air in the formation of dust devils?

What happens to the air at the bottom of a developing dust devil?

Why do dust devils persist for a period of time?

What is the main danger posed by microbursts to aircraft?

What is the shape of a dust devil once it is fully formed?

What is the primary purpose of calculating the Mean Cloud Layer (MCL)?

Which of the following techniques is used to forecast the base of cirrus clouds?

What is the primary factor in determining the turbulence category of an aircraft?

What is the purpose of the Richardson Number calculation?

What is the characteristic shape of a tropospheric temperature profile indicating potential turbulence?

What is the primary cause of moderate CAT during the development of an upper-level low?

What is the purpose of the CCL Parcel Method?

What is the primary factor in determining the base of stratus clouds?

What is the primary factor that determines the height to which a haboob can ascend?

What is the typical duration of a haboob?

What is the primary purpose of the Air Force Weather's ensemble products?

What is the characteristic of the lapse rate below the midlevel moisture surge in a haboob environment?

What is the name of the index that indicates the most unstable lifted condition in a haboob environment?

What is the approximate percentage increase in peak winds in a haboob compared to the speed of movement?

What is the average distance that a haboob can travel?

What is the purpose of the AFW WEBSTBT ensembles page?

What is the radiation fog point determined by?

What is the purpose of the radiation fog threat calculation?

What is the formula for the fog threat value?

What is the likelihood of radiation fog formation when the fog threat value is between 0 and 3?

How is the WBPT850 found if not already known?

What is the primary purpose of Figure 1.4?

What is the purpose of the radiation fog stability index?

What is the unit of the WBPT850?

What is the primary application of Table 1.2?

What is the primary difference between Figures 1.8 and 1.9?

What is the relationship between the fog threat value and the likelihood of radiation fog formation?

What is the primary purpose of Table 1.6?

What is the primary characteristic of Figure 1.11?

What is the primary application of Figure 1.10?

What is the primary difference between Table 1.4 and Table 1.5?

What is the primary purpose of Figure 1.6?

What is the phenomenon that causes haze particles to appear bluish when viewed against a dark background, but yellowish when viewed against a lighter background?

What is the primary factor that determines the visual range within a uniformly dense layer of haze?

Which of the following areas is most conducive to haze formation?

What is the primary difference between smoke and haze?

What is the critical factor in determining the occurrence of blowing dust and sand?

What is the term for the particles that form through the condensation or sublimation of atmospheric water vapor?

What is the primary difference between precipitation and blowing dust and sand?

What is the primary factor in determining the type of hydrometeors that form?

Why is dust detection more difficult in infrared imagery at night?

What is the reason for the improved dust detection in visible imagery over the Red Sea during the day?

What is the effect of forward scattering on dust detection in visible satellite imagery?

Why is the dust plume in Figure 1.9 more detectable at dawn?

What is the primary difference between dust detection in visible and infrared imagery?

What is the reason for the reduced thermal contrast between the dust and land at night?

What is the effect of backscattering on dust detection in visible satellite imagery?

Why is dust detection more difficult in infrared imagery over the Red Sea?

At what altitude does the potential haboob weaken?

What is the purpose of examining thunderstorm and blowing dust climatology?

What type of soil is most prone to dust lofting?

At what level should you look for long wave troughs and ridges when analyzing the synoptic environment?