Understanding Weather Hazards: Whiteout Conditions

Play an AI-generated podcast conversation about this lesson

What type of fog is associated with a warm front?

Post-frontal fog

Pre-frontal fog (correct)

Radiation fog

Desert fog

What is the OCDS-II example illustrating?

Visibility Climogram

WSCC example

Radiation Fog Point

OCDS-II (correct)

What does the Fog Stability Index (FSI) thresholds indicate?

Favorable conditions for dust advection

Snowfall intensity limits

Radiation fog formation likelihood (correct)

Dust lofting wind speeds

Where can you find the Threshold dust-lofting wind speeds for different desert environments?

Table 1.2 Signup and view all the answers

What do Fog threat thresholds indicate?

Radiation fog formation likelihood Signup and view all the answers

What should be examined at the 850 mb level to determine the presence of a nocturnal low-level jet stream?

Wind speeds Signup and view all the answers

Why are surface winds of at least 15 knots usually needed to loft dust?

To have sufficient force to lift and transport dust particles Signup and view all the answers

Which wind direction in Iraq is favorable for dust lofting?

North or northwest Signup and view all the answers

When does dust generally start to settle at the surface according to the text?

After dark once the nocturnal radiational inversion develops Signup and view all the answers

Why is analyzing wind speeds at the 925 mb level important?

To strengthen wind speeds at the surface and enhance dust lofting potential Signup and view all the answers

What is often conducive to momentum transfer from aloft that can enhance surface winds?

Dry low-level air Signup and view all the answers

What is the key ingredient required for dust storm generation after an appropriate source?

Lofting of dust particles by strong winds Signup and view all the answers

What is the role of wind shear in the lofting of dust particles?

Creating turbulence in the boundary layer Signup and view all the answers

At what range of wind speeds do the first sand and dust particles from 0.08 to 1 mm in diameter start to move?

15 to 25 knots Signup and view all the answers

What happens to the intensity of a dust storm even when wind speeds slow down?

It remains the same Signup and view all the answers

What is one of the effects of lakes drying up on soil and plant growth?

Inhibition of plant growth Signup and view all the answers

Which natural phenomenon in southern Iraq is responsible for many dust storms in the region?

Shamal events Signup and view all the answers

What does the Pollution Trapping Index (PTI) value indicate when it is greater than -40?

Minimal pollution trapping potential Signup and view all the answers

How is the Pollution Trapping Index (PTI) calculated?

PTI = -1.0 X (LAPSE + WIND^2) Signup and view all the answers

What do the blowing snow products from GEPS and MEPS indicate?

Indicate strong winds and snow accumulation but not necessarily visibility reduction Signup and view all the answers

Why could a drop in prevailing visibility from 25 miles to 15 miles be significant?

It may signal an unnoticed increase in low-level moisture Signup and view all the answers

What role does experience play in visibility forecasting according to the text?

Experience plays a significant role in visibility forecasting Signup and view all the answers

Why is sector visibility mentioned as significant in visibility forecasting?

Significant differences could suggest important occurrences Signup and view all the answers

What characteristics are important to consider when forecasting fog?

Synoptic situation, time of year, and station climatology Signup and view all the answers

Under what conditions may fog develop or intensify?

When air is supersaturated with respect to water in the presence of cloud condensation nuclei Signup and view all the answers

What must be the relationship between air temperature and dew point for fog to form?

Air temperature must equal the dew point (RH = 100%) Signup and view all the answers

What is a factor that contributes to the formation of visible cloud droplets in fog?

Presence of dust, soil, and other minerals in the air Signup and view all the answers

Which of the following is NOT a characteristic important to consider when forecasting fog?

Amount of precipitation in the area Signup and view all the answers

What does it mean for an air mass to be supersaturated regarding fog formation?

It has a relative humidity slightly greater than 100% Signup and view all the answers

Based on the text, which chart is used for contrail forecasting?

Appleman chart Signup and view all the answers

In the context of aircraft engines, what does the Appleman chart for high-bypass and low-bypass engines refer to?

Engine bypass type Signup and view all the answers

What do Planck curves for black bodies represent?

Emission of energy by an object Signup and view all the answers

Which table in the text compares the temperature of an object with its emitted energy?

Table 2.15 Signup and view all the answers

Based on the text, which figure provides information on probabilities of contrail formation based on temperature and pressure level?

Figure 2.44 Signup and view all the answers

What are the key factors influencing the duration of advected dust?

Depth of the dust and wind speed Signup and view all the answers

Which synoptic situation may change both the wind direction and the probability of dust advecting into an area?

Cold frontal passage Signup and view all the answers

What is a potential source of dust generation in agricultural areas?

Mechanical breaking of soil Signup and view all the answers

In which type of region can dust plumes be generated in advance of cold fronts?

Coastal areas Signup and view all the answers

What environmental condition is most prevalent in deserts where dust storms occur?

Scarce rainfall Signup and view all the answers

What factor can lead to increased dust potential beyond 36 hours following a rainstorm?

Soil evaporation after heavy rain Signup and view all the answers

What are the three major varieties of frontal dust storms mentioned in the text?

Prefrontal, postfrontal, shear-line Signup and view all the answers

What is the primary factor that distinguishes frontal dust storms from shamals?

Scale of the weather systems Signup and view all the answers

In which quadrant of a jet streak is there an increase in upward vertical velocities according to the text?

Left-front Signup and view all the answers

What are prefrontal winds called in Saudi Arabia according to the text?

Kaus Signup and view all the answers

Why are prefrontal dust storms difficult to detect in METSAT imagery?

Their short-lived nature Signup and view all the answers

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

$15-20$ knots Signup and view all the answers

What does a negative Lifted Index (LI) value (less than -2) indicate?

High likelihood of convection later in the day Signup and view all the answers

When determining the maximum relative humidity (RH) in the 700 mb to 400 mb layer, what RH percentage is associated with precipitation aloft?

Around 90% Signup and view all the answers

What is the impact of water droplets falling into a deep, dry planetary boundary layer (PBL)?

Cools and moistens the PBL Signup and view all the answers

In which layer and at what temperature do ice crystals form from water vapor according to the text?

700-400 mb layer at temperatures below -5°C Signup and view all the answers

What is the significance of high relative humidity (above 90%) at temperatures below -5°C in the 700-400 mb layer according to the text?

Strengthens potential downdrafts Signup and view all the answers

What does analyzing mid-level moisture aim to assess in atmospheric conditions?

Negatively buoyant downdraft potential Signup and view all the answers

What typically delineates the top of the planetary boundary layer where haze layers are found?

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

Under what conditions can haze persist for days according to the text?

When atmospheric conditions are stagnant and there is no cleansing mechanism like precipitation Signup and view all the answers

What atmospheric conditions can favor the formation of sulfate aerosols, leading to the creation of haze?

Plenty of sun, increasing boundary layer moisture, and limited mixing Signup and view all the answers

What factor can lead to the dissipation of haze according to the text?

Thermal instability or increase in wind speeds Signup and view all the answers

What range of visibility is typically restricted by haze according to the text?

Less than 1 mile occasionally Signup and view all the answers

In what regions can elevated haze layers occur according to the text?

Regions downstream from where particles are lofted above the PBL by cumulus clouds Signup and view all the answers