Meteorology Past Paper PDF

METEOROLOGY 1. Explain the Coriolis Force Coriolis Force is described as the force created by the rotation of the Earth that deflects static circulation patterns. In another sense, it is the force that pulls objects, especially those traveling in long distances such as air cur...

METEOROLOGY 1. Explain the Coriolis Force Coriolis Force is described as the force created by the rotation of the Earth that deflects static circulation patterns. In another sense, it is the force that pulls objects, especially those traveling in long distances such as air currents and water currents, to the clockwise direction in the northern hemisphere, and counterclockwise direction in the southern hemisphere. 2. What is a microburst? Microbursts are small-scale intense downdrafts which, upon reaching the surface, spread horizontally outwards in all directions from the downdraft center. Microbursts are 1 mile horizontally from thunderstorms, 1,000 ft vertically, 6,000ft per minute downdraft, and could usually last within 15 minutes. 3. What is the difference between stable air and unstable air? The difference between stable air and unstable air can be observed with the following difference in characteristics: one is in the clouds wherein the clouds for stable air is stratus type, while unstable air have cumulus types of clouds. For precipitation, stable air has steady precipitation, while unstable air has showery precipitation. Stable air has smooth and stable air, while unstable air is turbulent. As for the winds, winds for stable air are described as steady, while unstable air have gusty winds. Lastly, for visibility, stable air has poor visibility, while unstable air has good visibility. 4. What is an inversion and what are its types? Inversion occurs when cool air is trapped underneath a layer of warm air. This develops due to the air near the ground cooling more quickly than the air aloft or above it, reversing their temperature profile, which results in the creation of a stable configuration of dense cold air sitting below lighter warm air. 5. Decode the TAF below. TAF 012300Z 0200/0306 05000KT 9999 FEW025 SCT100 TX33/0203Z TN260221Z TEMPO 0200/0206 07012KT FEW023 BKN100 TEMPO 0206/0212 09012KT SCT023 BKN100= TAF - Terminal Aerodrome Forecast RPLL - Manila International Airport / Ninoy Aquino International Airport 012300Z - 1st of the Month, 23:00 UTC 0200/0306 - Valid from 2nd of the Month, at 00:00 UTC to the 3rd of the Month, 06:00 UTC. 05005KT - Winds heading 50 degrees at 5 knots 9999 - Unlimited visibility FEW025 SCT100 - few clouds at 2,500 ft., and scattered clouds at 10,000 ft. TX33/0203Z TN26/0221Z - Maximum temperature of 33 Degrees Celsius valid on the 2nd of the Month 03:00 UTC, and Minimum temperature of 26 Degrees Celsius valid on the 2nd of the Month, 21:00 UTC TEMPO 0200/0206 07012KT FEW023 BKN100 - temporary variations valid on the 2nd of the month, from 00:00 UTC to 06:00 UTC with winds heading 70 degrees at 12 knots, with few clouds at 2,300ft and broken clouds at 10,000ft. TEMPO 0206/0212 09012KT SCT023 BKN100= - temporary variations valid on the 2nd of the month, from 06:00 UTC to 12:00 UTC with winds heading 90 degrees at 12 knots, with scattered clouds at 2,300ft and broken clouds at 10,000ft. End of report METEOROLOGY ○ The primary reason why winds are generated Why is MET important to pilots? (+Coriolis Force due to the rotation of the Earth ○ “Weather is an important factor that influences on its axis) aircraft and flying safely” (FAA, 2016) Convection / Process of Convection ○ Pilots are expected to have fundamental ○ Circulating motion that results when warm air knowledge of weather theory. rises and is replaced by cool/er air ○ Additionally, pilots should know how to access ○ High Air Pressure🠊Low Pressure Area and interpret the services available forecasting ○ Cold air goes down because it is denser than hot weather conditions air The branch of science that deals with the physical ○ Hot air rises because it is less dense than cold properties of the atmosphere air Deals with how the weather conditions develop and Coriolis Force change ○ Force created by the rotation of the Earth that deflect static circulation patterns ATMOSPHERE ○ Towards equator = falling behind Blanket of air made up of a mixture of gasses that ○ Moving away = pulling ahead surrounds the Earth ○ Earth rotates faster at the Equator than it does at Layers of the atmosphere the poles. ○ 2°C per 1,000ft. Increase of altitude up to 36,000ft. ○ 1 in. Hg per 1,000ft increase of altitude Earth’s Atmosphere: ○ 78% Nitrogen ○ 21% Oxygen ○ 1% Other gases Layers of the Earth’s Atmosphere: ○ Troposphere (20,000 ft) Lowest, closest layer of atmosphere to the Earth Layer closest to Earth; 6 to 7 miles from Earth’s atmosphere Characterized by a decrease in temperature with altitude Where weather begins ○ Stratosphere (160,000ft) Hadley Cells Much of the same composition as the Equator: warmer (less dense) air rises Troposphere ○ Rises to a height of above 18 KM and spread out Certain types of clouds occasionally underneath the tropopause extend to it Tropopause: Acts as a lid to the lowest part of our Severe thunderstorms occur here (19 to atmosphere 22 miles) Largest Cells Where temperature increases with the Polar Cells increase in altitude Cold dense air descending into the polar regions flow at Severe thunderstorms (towering low levels to about 60° to 90° North or South cumulus) As the air leaves the polar regions it starts to warm and ○ Mesosphere (280,000 ft) rise, returning to the poles at high levels 45 to 51 miles Ferrel Cells ○ Thermosphere (350 miles) Not driven by temperature Outermost layer of the atmosphere Flow in the opposite direction to the Hadley & Polar Cells ○ Exosphere acting like a gear NOTE: EQUATOR — hottest part of the Earth due to the Where weather Earth’s tilt NOTE: ATMOSPHERIC CIRCULATION These cells not only transport heat from the equator to Uneven heating of Earth’s surface the poles but also result in semi-permanent areas of low ○ The root cause of all atmospheric events pressure and high pressure. Higher pressure, higher temperature Where air is rising, an area of low pressure is create, so Low pressure, lower temperature these areas see much more rainfall ○ Uneven heating because of the Earth’s tilting, Where air is descending, an area of high pressure forms revolution, rotation; the angle in which the sun giving largely clear skies and little rainfall hits the Earth, type of surface, ○ Because the world is a circle / sphere, heat focuses on the equator, thus uneven heating  ○ Unable to sail and resupply due to lack of wind, crews often ran out of drinking water. To conserve scarce water, sailors on these ships would sometimes throw the horses they were transporting overboard GLOBAL WIND PATTERNS Polar Easterlies — 60° –90°, dry cold from the EAST ○ From polar highs (HPA) around SH and NH to LPA in subpolar regions Westerlies — 30°–60°, blows from WEST at midlatitudes INTERNATIONAL STANDARD ATMOSPHERE CONDITION (ISA) ○ Fed by polar easterlies from high pressure horse Standard Sea Level Pressure latitudes 29.92 in Hg or 1013 mb/hPa Tropical Easterlies (Trade Winds) — 0°–30° Standard Sea Level Temperature ○ Powerful prevailing winds that blow from the 15°C / 59°F EAST across the tropics Standard Lapse Rate ○ Continental trade winds (warmer drier, over land) For every 1,000 ft increase in altitude: vs maritime trade winds ○ Decrease of 2°C in temperature ○ Relationship between continental and maritime ○ Altitude: decrease in 1 in. Hg trade winds can be violent ○ Tropical storms (hurricanes, cyclones, typhoons) ATMOSPHERIC PRESSURE AND TEMPERATURE develop as trade winds ISA TEMPERATURE DEVIATION ○ Differences in air pressure over the ocean cause these tropical storms to develop (as dense moist ( 𝐴𝐿𝑇 ) 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 = 15 − ⎡ 1000 × 2⎤ ⎣ ⎦ winds of the storm encounter drier winds of the 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 𝐷𝐸𝑉 = 𝐴𝐶𝑇𝑈𝐴𝐿 𝑇𝐸𝑀𝑃 − 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 coast, the storm can increase intensity) ISA TEMP DEV is the difference between ISA Doldrums — where trade winds of the two hemispheres temperature and Actual temperature meet is called the intertropical convergence zone (ITCZ) Significance: ○ Area around ITCZ is the doldrums ○ Fuel Efficiency ○ Prevailing winds in doldrums are very weak, ○ Engine Performance weather is unusually calm ○ Pressure and Density Altitude ○ Doldrums – “refers to the belt around the Earth ○ Equipment Protection near the equator where sailing ships sometimes ISA PRESSURE DEVIATION get stuck on windless waters.” ISA PRESSURE ○ Doldrums ( 𝐴𝐿𝑇 ) 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 = 29. 92 − ⎡ 1000 × 0. 03⎤ ⎣ ⎦ Located in the equator (0°–5° latitude) 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 𝐷𝐸𝑉 = 𝐴𝐶𝑇𝑈𝐴𝐿 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 − 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 experience very little wind because of 𝐴𝐶𝑇𝑈𝐴𝐿 = 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 𝐷𝐸𝑉 + 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 convergence of trade winds and westerlies ⎣ ( ) 𝐴𝐿𝑇 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸(𝐴𝑇 𝑀𝑆𝐿) = 29. 92 − ⎡ 30 × 0. 03⎤ ⎦ Intertropical Convergence Zone Due to the equator directly exposed to EXAMPLE (ISA TEMP) the sun, hence, why the air moves FIND: ISA TEMP & ISA TEMP DEV horizontally GIVEN: Horse Latitudes ALT = 30,000 ○ Located at 30° North and South that experiences OAT = -50 little wind 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 𝐷𝐸𝑉 = 𝐴𝐶𝑇𝑈𝐴𝐿 𝑇𝐸𝑀𝑃 − 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 ○ Narrow zone of warm, dry climates between ( 𝐴𝐿𝑇 ) 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 = 15 − ⎡ 1000 × 2⎤ ⎣ ⎦ westerlies and trade winds ○ Areas of high pressure and thus winds go separate waves from one another searching for ( 30,000 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 = 15 − ⎡ 1000 × 2⎤ ⎣ ⎦ ) pockets of low pressure 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 = 15 − [(30) × 2] 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 = 15 − 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 =− 45 EFFECTS OF ATMOSPHERIC PRESSURE ON FLIGHT 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 𝐷𝐸𝑉 = 𝐴𝐶𝑇𝑈𝐴𝐿 𝑇𝐸𝑀𝑃 − 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 Decreased atmospheric pressure results in: 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 𝐷𝐸𝑉 =− 50 − (− 45) Decreased aircraft performance 𝐼𝑆𝐴 𝑇𝐸𝑀𝑃 𝐷𝐸𝑉 =− 5 EXAMPLE (ISA PRESSURE) EFFECTS OF ATMOSPHERIC PRESSURE ON THE HUMAN BODY ALT = 7400 ft Decreased atmospheric pressure results in decreased QNH: 29.76” Hg partial pressure of oxygen FIND: ISA Pressure Dev at that altitude ○ Difficulty in breathing ( ) 𝐴𝐿𝑇 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 = 29. 92 − ⎡ 1000 × 0. 03⎤ ⎣ ⎦ ○ Actions are impaired at an altitude of 10,000ft. NOTES: The land warms up and cools off faster than water ( ) 7400 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 = 29. 92 − ⎡ 1000 × 0. 03⎤ ⎣ ⎦ Warm air is less dense than cold air and will rise and 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 = 29. 92 − [0. 222] create low pressure 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸𝐴𝑇 7400 = 29. 698 Cold air is more dense than warm air, and will sink, creating high pressure Air will always move from high pressure to low pressure ALT = 4800 ft ○ “High to low is the only way the atmosphere will ISA DEVAT 4800 ft = -1.77” Hg go” FIND: QNH at MSL A low pressure zone forms above the land surface from the rapid loss of heat ⎣ ( ) 𝐴𝐿𝑇 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 = 29. 92 − ⎡ 30 × 0. 03⎤ ⎦ A high pressure zone forms as the cooler lands cools the 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 = 29. 92 − [4. 8] air immediately above the surface 𝐼𝑆𝐴 𝑃𝑅𝐸𝑆𝑆𝑈𝑅𝐸 = 25. 12 WHAT ARE WINDS? 𝑄𝑁𝐻𝑎𝑡 𝑀𝑆𝐿 =− 1. 77 + 25. 12 The result of air flowing from regions of high pressure to 𝑄𝑁𝐻𝑎𝑡 𝑀𝑆𝐿 = 23. 35 regions of low pressure or, Coriolis Force Winds are partly responsible for the weather phenomenon. PRESSURE VARIATION Varies horizontally due to unequal heating of the Earth LOCAL WIND PATTERNS Varies diurnally (during the day) 1. Sea Breeze (DAY) ○ Reaching peaks at 1000H AND 2200H Wind that blows from the cool water TO the ○ And lows at 0400H and 1600H warmer land ○ Varies diurnally because of tidal action, get FROM Cool Water TO Warm Land ○ Moon is nearest the earth it gets pulled, farthest Movement is caused by the difference in it gets pushed pressure between cooler (more dense) sea and Pressure is inversely proportional to _temperature_ warmer land Pressure is directly proportional with DA High Pressure (cooled air sinking) TO Low ○ Go up, pressure goes down Pressure (air about to rise) Bernoulli – 2. Land Breeze (NIGHT) Varies about 3 hectopascal Wind that blows from the cooler land TO the PRESSURE (hPa) APPROXIMATE HEIGHT (FT) warmer water 850 5,000 AMSL Land cools more easily than water, so Cool Land 700 10,000 AMSL breeze (HP) goes to warmer water (LP), 500 18,000 AMSL Water has higher heat retention – when it “cools 400 24,000 AMSL down” at night, releasing heat, the heat rises, 300 30,000 AMSL cools down, and sinks back to the cooler ground 200 40,000 AMSL (ground is COOL because it has lower heat 100 53,000 AMSL retention vs water/more easily cools down). 50 68,000 AMSL PRESSURE VALUES QFE — The pressure at the datum level of the airfield or aerodrome QNH — The QFE reduced to MSL using ISA conditons QNE — ISA Sea Level Pressure (29.92” Hg or 1013 mb/hPa AIR DENSITY Air density is the amount (mass) of air per unit volume ○ Varies directly proportional to air pressure ○ Varies inversely proportional to temperature ○ Varies inversely proportional to humidity of the air  Convective Currents Causes the bumpy, turbulent air sometimes experienced when flying at lower altitudes during warmer weather On a low altitude flight: ○ Updrafts are likely to occur over pavement or barren places (ie., Tarmac) During the day, land heats faster than water, so the air over the land becomes warmer and less dense TURBULENCE Sudden,violent shift in airflow caused by irregular atmospheric motion Types ○ Light — Vertical displacement of up to 1 meter ○ Moderate — Vertical displacement of 3-6 meters ○ Severe — Vertical displacement of up to 30 meter Wind Shear / Low Level Wind Shear ○ Sudden and drastic change in wind direction (up to 180) and velocity (up to 50 KTS) ○ Can occur at any altitude in vertical and 3. Valley Wind (DAY, Upslope movement) horizontal directions Cooler valley air SINKS pushing the warmer air ○ Can subject aircrafts to sudden updrafts and close to mountain slopes UPWARDS (following downdrafts the shape of the valley) ○ Often associated with convective precipitation ○ Warm air on close to mountain slopes is ○ Common types: Microburst DUE to sun heating up the slopes of the Occurs within less than one mile valley/mountain horizontally and within 1,000ft vertically ○ LAND heats more quickly of a thunderstorm Hot/warm air rises adjacent to the slope and cool Lasts for 15 minutes, 6,000fpm air pushes warm air from inwards up the slope of downdrafts the valleys/mountains Chop 4. Mountain Wind (NIGHT, Downslope movement) Light — turbulence that causes slight, rapid, and Cooler air flows down the slope and displaces so the air in the valley Moderate During the night when land cools more quickly, Occasional cool dense air on slopes of mountain SINK, displacing warm air above it. WIND OBSTRUCTIONS Cool dense more heavy air (Slope) sinks pushing Mechanical that result in chaotic airflow warm air upwards (also because HP wants to go Obstruction on the ground affect the flow of wind and to LP) then cools down at an altitude, then sinks can be unseen danger back Ground topography and large buildings can break up the flow of wind and create wind gusts that change rapidly in direction and speed. JET STREAMS Fast moving streams of air at higher altitudes blowing eastward Caused by “breaks” in the tropopause, effect of Coriolis force and the heating of the circulating cells Polar Jet Streams – 23,000 to 29,000 FT ○ Forms near the boundary between Ferrel and Polar Cells Subtropical Jet Stream – 4 to 8 Miles / FL210 to FL420 ○ Forms near boundary between Hadley and Ferrel Cells Can reach speeds up to 239 Kts Check turbulence / jet stream at Prognostic Chart You go where the Jet Stream (for the Tailwind) are for: ○ Efficiency ○ Time management Fast moving streams ○ Summer Weak North (mas mabilis polar) WINDS AND CURRENTS ○ Winter Strong South (mas mabilis si subtropical; Uneven surface heating leads to convective currents due to Amihan (east), wind coming from north)  Dahil malamig nanggagaling from North, ○ Low pressure surrounded by high it sinks) pressure Double line = change bar or breaks – indicates ○ Orientation of the wind is counter change in jet stream speed clockwise (NH, and clockwise in SH) Pagnagsalubong yung turns/gears nung cells, that’s ○ Weather dominated by moist, strong when Jet Stream occurs winds/unstable air, and low visibility Isobars, Col, ○ Cloudy and wet ○ Additional Characteristics: WIND SYMBOLS thunderstorms, generally fast, associated with troughs (elongated area of LP, has the worst weather) Ridged — an elongated area of HPA Trough — an elongated area of LPA Col — a neutral area of two high’s and two low’s ○ Region sandwiched by two HPAs and two LPAs ○ or an intersection of a ridge and trough Typhoons / Tropical Cyclones = All storms coming from WESTERN PACIFIC (wet, hot/moist) Hurricane = EASTERN PACIFIC + Atlantic (Winds are dry and cold) PRESSURE SYSTEMS High Pressure – Malaki pressure sa gitna, Converges more vs a Low Pressure Low Pressure – Lowest at the center Both diverging and converging ATMOSPHERIC STABILITY STABILITY OF AIR Combined effects of temperature and moisture determines stability of air and types of weather product STABILITY – Dictates resistance to vertical movement ○ “Resistance to creation of clouds” Stable Air (evident in Polar regions) Unstable Air ABSOLUTE INSTABILITY ○ occurs when dry adiabatic rate is less than the WINDS AND PRESSURE REPRESENTATION environmental lapse rate Pressure and Winds ○ Unstable in all altitudes (di nawawala yung A. Isobars moisture, it will continue to develop into a storm) A line on a weather chart that shows equal or ○ In this case, an air parcel will be warmer and less constant barometric pressure dense than the surrounding air and will rise due Identifies pressure systems as: High, Low, to buoyant forces. Ridges, Trough ○ Air Parcel is Warmer than the environment Widely spaced isobars — shallow pressure ○ Kahit anong angat gradient and relatively light winds ○ Thunderstorm - moist unstable air with lifting Closely spaced isobars — steep pressure action gradient and strong winds B. Pressure Gradient Representation of change in pressure over a given distance C. Pressure Systems High — Anti-cyclonic; high pressure; clockwise ○ Center of high pressure surrounded on all sides by a low pressure ○ Clockwise in the Northern Hemisphere and anti-clockwise in the Southern Hemisphere ○ Additional Characteristics: fair winds, clear skies, slow moving, usually associated with ridge (elongated area of high pressure) Low — Cyclonic; depression; counter clockwise ATMOSPHERIC STABILITY CHARACTERISTICS Basically, when warm air mass meets cold air STABLE CHARACTERISTICS UNSTABLE mass, the warm air rises (less dense) over the Stratus CLOUDS Cumulus denser cold air. Steady PRECIPITATION Showery ○ Warm air ascends, cools, and creates Stable/Smooth AIR Turbulent inversion layer, trapping the colder air Steady WIND Gusty near the ground beneath the warmer air Poor VISIBILITY Good aloft Stable Air — Cold and Dry; No tendency ○ (air near the ground cools more quickly (eg., Poles) because again, LAND expels heat Unstable — Warm and Moist; common in tropical areas quickly) (eg., Philippines) NOTES Rising air in the atmosphere creates an unstable air 3. MARINE INVERSION environment Cool, moist, and stable marine air moves Stable Air: beneath layer of warm, dry, unstable air over ○ Stratus clouds resist the rising warm air in the lowlands along the coast often with sea breeze atmosphere Occurs when cool, moist air originating from the ○ vertical motion is inhibited ocean is blown onto land by prevailing winds/sea ○ if clouds form, they will be shallow, layered breeze. clouds (ie., stratus clouds) ○ The cool temperature of this air makes it Unstable Air: more dense, so it readily flows ○ Clouds develop into cumulus clouds because of underneath the warmer, drier air present the rising warm air in the atmosphere over/from the land ○ Vertical motion occurs Commonly found along the shorelines of large ○ Commonly produces cumulus, cumulonimbus lakes, along coasts of continents clouds Strongest and most noticeable at night; can INVERSION persist during the day A layer of air where temperature rises as altitude rises/increases 4. SUBSIDENCE INVERSION Shallow layers of smooth, stable air close to the ground Typically occur under high-pressure systems Could occur in stable air with little or no wind and and clear skies turbulence Occurs when large air mass sinks and TYPES OF INVERSION compresses, thus, heats up 1. SURFACE-BASED INVERSION / NIGHT TIME / RADIATION ○ Cool air is trying to rise, but is trapped by Occur on clear, cool nights when the air close to the warmer air above the ground is cooled by the lowering Occurs when an area of high pressure causes a temperature of the ground layer of air to subside or sink Air within a few hundred feet off the surface ○ The air compresses and dries out as it becomes cooler than air above/aloft it descends, allowing it to warm up Forms when air near the cooling ground cools Subsidence inversion — is an increase in quickly through conduction temperature with increasing height produced by Will result to ground fog (less than 50 ft), if slow sinking of a layer of middle/high level high temperature of surface air drops below its dew pressure point. ○ As high-altitude air sinks (subsides), it warms by compression, producing layer 2. FRONTAL INVERSION of warm, dry, and very stable air Associated with the passage of fronts (cold front SInking of cold air going to the ground and warm front). Warm When (a) warm air spreads over cooler air, OR (b) cooler air is forced under the layer of warm air Frontal – mayroong air, kaya may oppenheimer sa ilalim (where (a) Forms when a layer of cold air near the warm and cool air converges) ground moves under and displaces upward a layer of warmer/less dense air Subsidence – it’s a compressed and sinking air ○ Inversion-forming occurs with the - Compressed air comes from higher altitude which sinks passage of a cold front down (b) Can also form when layer of warm/less dense air slides up and over a layer of colder/more HUMIDITY dense air near the ground Moisture content in the air ○ Inversion-forming occurs prior to the Dependent on the ambient air temperature passage of warm front Occurs when cold air mass undercuts warm air RELATIVE HUMIDITY mass and lifts it aloft (warm air above, cold air Actual amount of moisture in the air compared to the below) - humidity may be high and clouds may be total amount that could be present at that temperature present immediately above it  “As it cools, it loses its ability to hold lots of DEW, FROST, AND FOG water/moisture” DEW Present in the parcel of air vs maximum it can hold at a Forms when water vapor condenses and deposits itself certain temperature on a surface as a result of air being cooled by the ground FROST DEW POINT Frost forms like dew but with the temperature at or below Temperature at which air reaches a state where it can freezing hold no more water/water vapor/moisture Forms when water vapor changes directly to ice on a temperature to which it must be cooled to become surface that is below freezing saturated with water vapor. FOG ○ When temperature of air is reduced to the dew Water droplets suspended in the air point, air is completely saturated, and moisture Visible moisture with the base within 50 ft on the ground begins to condense out of the air in the form of Cloud that is on the surface fog, dew, frost, clouds, rain, or snow A cool air that is breezed upon/mixed by warm air (from Can be not yet 100% but it already saturated the sun) NOTE: Decrease in air temperature, decrease in ability to Fog forms because the area is cool, then there is sun that hold water; increase air temperature, increased ability to produces heat, that’s why fog is formed hold water MIST - Visibility: Greater than 1KM 𝐴𝑃𝑃𝑅𝑂𝑋 𝐶𝐿𝑂𝑈𝐷 𝐵𝐴𝑆𝐸 ≈ (𝑇𝐸𝑀𝑃−𝐷𝐸𝑊 𝑃𝑂𝐼𝑁𝑇) × 1, 000 FOG - Visibility: Less than 1KM 2.5 𝐶 (𝑜𝑟 4.4 𝐹) (𝐺𝑅𝑂𝑈𝑁𝐷 𝑇𝐸𝑀𝑃 − 𝐷𝐸𝑊 𝑃𝑂𝐼𝑁𝑇) × 400 TYPES OF FOGS 1. GROUND / RADIATION FOG NOTES: Fog less than 20 ft deep Relative humidity rises when temperature drops On clear nights, with relatively little to no wind As temperature increases, it will lead to a decrease in present relative humidity, thus air will becomes drier Usually forms in low-lying areas like mountain When temperature decreases, the air will become wet, valleys this means that relative humidity increases Occurs when the ground cools rapidly due to “As air temperature increases, air can hold more water terrestrial radiation, and the surrounding molecules, and its relative humidity decreases. When temperature reaches its dew point temperatures drop, relative humidity increases.” Cooled by rain or radiation cooling does not require any wind to form METHODS OF ADDING MOISTURE TO THE AIR Usually dissipates after sunrise as the ground Evaporation — Liquid to Gas warms Condensation — Gas to Liquid (water vapor to liquid) 2. ADVECTION FOG Process of making clouds Warm moist air moves over the cool surface Sublimation — Solid to Gas (without becoming liquid) (land or sea) Example: Dry ice (a frozen form of carbon Require wind to form dioxide) ○ Wind will push warm air over the cool Deposition — Gas (Water vapor) to solid surface to form the advection fog Example: Frost - water vapor in atmosphere ○ Winds up to 15 knots allow the fog to changes directly into ice crystals form and intensify Example: Creation of dry ice ○ 15+ knots: fog hits and form stratus Melting — Solid to Liquid clouds Freezing — Liquid to Solid Dissipates with the warming of the surface (e.g., all the snow melts, or there is significant solar METHODS OF REACHING SATURATION POINT heating), and/or if the wind changes direction, Air cools and reaches its saturation point when: allowing the conditions that created the 1. Warm air moves over a cold surface advection fog to disappear. 1. Temperature drops 3. UPSLOPE FOG 2. Surface is cold, warm air will go through cold Occurs when moist, stable air is forced up surface, water vapor will condense, and it will sloping land features like a mountain range become dew (thus reaching its saturation point) Requires wind for formation and can persist for 3. “Reaches the equilibrium wherein it can no longer days (requires wind as well to dissipate) hold moisture” Occurs when sloping terrain lifts air, cooling it 2. Cold air and warm air meet (passage of fronts) adiabatically to its dew point and saturation 3. Air cools at night through contact with the cool ground As moist winds blow toward a mountain, it glides (air cools through conduction via cooled ground) and this causes the air to rise and cool. 4. Air is lifted or forced upward in the atmosphere (warm air Generally forms at the higher altitudes and builds rises and is cooled in the atmosphere) (aka, process of downward into valleys. convection/convection) Can maintain at higher wind speeds because of increased lift and adiabatic cooling. When Saturation is reached, that’s when condensation occurs or Can even result to a lenticular clouds May not burn off with the morning sun  4. STEAM / EVAPORATION / SEA FOG ○ Below 6500 up to 60,000 ft Occurs when evaporation takes place into cold ○ Towering cumulus to Cumulonimbus air lying over warmer water ○ Cumulus – start of a thunderstorm Forms when cold, dry air moves over warm water Low Level Clouds As the water evaporates, it rises and resembles 1. Stratus smoke Layered clouds that form in stable air near the Over borders of water during cold times of the surface due to cooling from below year Stratus = spreading, cover, layer, low altitude Invisible vapor is given off from the water but is 2. Stratocumulus / Cumulostratus almost immediately recondensed as it comes White puffy clouds into contact with the colder air. large, rounded masses of stratus that form Air has to be much colder than water so that groups, lines or waves. convection currents develop large dark, rounded masses, usually in groups, ** Same concept as Advection Fog lines, or waves, individual elements being larger Change of temperature allows dissipation of this than those in altocumulus; at a lower altitude type of fog. 3. Cumulus Can cause icing for aircraft as it occurs during “Cumulus” = accumulation, a heap, a pile. the night, poorer aircraft performance due to Dense puffy cloud form having a flat base and presence of moisture. rounded outlines often piled up like a mountain 5. PRECIPITATION FOG 4. Nimbostratus Fog that forms when rain is falling through cold Gray or black, more than a several thousand feet air thick Cold air, dry at the surface while rain is falling Mid-Level Clouds through it, evaporates and causes the dew point 5. Altostratus Warm rain moving onto cooler surface Flat, dense clouds covering a wide area with gray 6. ICE FOG or white clouds Occurs in cold weather when temperature is 6. Altocumulus much below freezing and water vapor (steam) Gray/white patchy clouds forms directly into ice crystals High Level Clouds Arctic regions or in very cold temperatures 7. Cirrostratus SMOG Thin, white long sheets against a blue The combination of smoke and fog that causes poor background visibility - caused by air pollution 8. Cirrocumulus HAZE White patchy like cotton Caused by the concentration of very fine salt or dust 9. Cirrus particles suspended in the air (eg., urban areas) Thin, wispy; narrow band CLOUDS Composed of very small droplets of water Visible moisture that has condensed or sublimated onto condensation nuclei ○ Condensation Nuclei = cloud seeds ○ Tiny particles in the air on which water vapor condenses (solid particles, or water particles that enable/helps the formation of clouds; dust, salt, water particles) Small water droplets/dust particles are required to form clouds CLOUD FORMATIONS (SPECIAL CLOUDS) TYPES OF CLOUDS (BASED ON HEIGHT) 1. Castellanus Clouds Low Clouds (Surface Level – 6,500 AGL) Can be found amongst 4 cloud types: cirrus, ○ Stratus, Stratocumulus, Nimbostratus, Cumulus cirrocumulus, altocumulus, and stratocumulus Middle Clouds (6,500 AGL – 20,000 AGL) Caused by unstable air heated from below rising ○ Altostratus & Altocumulus rapidly causing water droplets to condense ○ Water droplets, ice crystals, and supercooled Occur when instability only starts at higher water droplets altitudes ○ Light turbulence Same base, different heights / vertical ○ Moderate icing developments High Clouds (20,000 AGL +) ○ Cirrostratus, Cirrocumulus, Cirrus ○ No real threat of turbulence or aircraft icing ○ Usually forms in stable air Clouds with Vertical Development  When wind speed is sufficiently strong and perpendicular, or nearly-perpendicular to mountain ranges, waves develop over and downstream of the barriers. If enough moisture is present in the air, clouds develop in the portion of the wave with upward vertical motions. Wind speeds may be as fast as 30KTS of greater The waves remain nearly stationary for periods up to several hours. While visually appealing in the form of lenticular clouds, these waves are often associated with turbulence and are considered to be an aviation hazard 2. Fractus/Ragged Clouds Small, ragged cloud fragments that are usually found under an ambient cloud base Found only in low-altitude cumulus and stratus clouds type They form or have broken off from a larger cloud, and are generally sheared by strong winds, giving them a jagged, shredded appearance. 5. Broken Clouds conditions in which clouds cover five-tenths to nine-tenths of the sky. 3. Lenticular Clouds The sky is mostly cloudy, but occasional sunlight Forms when the air is stable and the winds blow breaks through. across hills and mountains from the same Overcast skies are defined as a sky fully covered direction at different heights through the by clouds. troposphere Commonly forms downwind of hills/mountains When air blows across a mountain range, it can form a train of large standing waves in the air downstream like ripples forming in a river when water flows over an obstruction. If enough moisture is present, the rising motion of the wave will cause water vapor to condense, forming the unique appearance of lenticular clouds. Considered as visible signs of mountain waves TYPES: altocumulus lenticularis, stratocumulus lenticularis, cirrocumulus lenticularis (varies in altitude above ground) 6. Mammatus Clouds Appear like bumpy or pouch-like structures hanging from the undersides of other types of clouds, typically thunderstorm clouds Usually formed in association with large cumulonimbus clouds Turbulence within the cumulonimbus clouds will cause mammatus to form, especially on the underside of the projecting anvil as it rapidly 4. Altocumulus Lenticularis descends to lower levels Altocumulus + Lenticular clouds = altocumulus Mammatus clouds form in the most unstable clouds that are lens-shaped cumulonimbus = strong chance of hail, heavy Typically associated with stable air patterns rain, lighting within vicinity (if cold enough in often seen near mountains or hilly terrain (air winter, may also produce snow) flows over obstacles, creating these unique cloud Usually form on the base of cumulonimbus anvil formations but have also been sighted on stratocumulus, Can be a sign of **mountain waves altostratus, altocumulus, and even on the Common in areas with frequent atmospheric underside of volcanic ash clouds disturbance caused by terrain effects Read More: [a] [b] ** Mountain Waves TYPES OF CLOUDS CLOUD TYPE HEIGHT COMPOSITION TURBULENCE & ICING CIRRUS (CI) 16,500 – 45,000 Ice crystals NIL CIRROSTRATUS 16,500 – 45,000 Ice crystals NIL (CS) CIRROCUMULUS 16,500 – 45,000 Ice crystals LIGHT / NIL (CC) ALTOCUMULUS 6500 — 23,000 Water droplets + LIGHT – MOD (AC) ice crystals ALTOSTRATUS 6500 — 23,000 Water droplets + LIGHT – MOD (AS) ice crystals ALTOCUMULUS 6500 — 23000 Water droplets + MOD – SEV CASTELLANUS ice crystals (ACC) ALTOCUMULUS 6500 —23,000 Water droplets + MOD – SEV LENTICULARIS ice crystals (ACL) CUMULONIMBUS 1,000 — 45,000 Water droplets + MOD – SEV CLOUD CEILING (CB) ice crystals Vertical distance between ground level and the base of CUMULUS (CU) 1,000 — 25,000 Water droplets + MOD – SEV the lowest layer of broken or overcast clouds ice crystals Parameters: Ceiling is less than 1,500 ft or ground STRATOCUMULUS 1,000 — 6,500 Water droplets LIGHT – MOD visibility is less than 5KM (SC) Low Ceiling – Good slant visibility NIMBOSTRATUS SFC — 6,500 Water droplets + MOD – SEV ○ Clouds, but clear sa ilalim (NS) ice crystals Indefinite Ceiling – Walang ceiling, you can only see STRATUS (ST) SFC — 6,500 Water droplets NIL – LIGHT vertical visibility ○ Poor slant range CLOUD PROPERTIES ○ Foggy area or inside clouds SKY/CLOUD COVER – Fraction of the sky obscured by clouds OKTA Unit of measurement used to describe the amount of cloud cover at any given location such as weather station Aviation Weather ○ SKC - Sky Clear (0 Okta) ○ FEW - Few (1-2 Oktas) ○ SCT - Scattered (3-4 Oktas) ○ BKN - Broken (5-7 Oktas) ○ OVC - Overcast (8 Oktas) VISIBILITY Greatest horizontal distance at which prominent objects can be seen Measure of the distance at which an object or light can be clearly discerned PRECIPITATION Any type of water that form in the atmosphere and fall to the ground Drizzle — rain smaller than ⌀ = 0.02” RAIN  Water droplets that falls as liquid water when 1. Two air masses of different densities temperatures in the air and at the surface are above must exist adjacent to one another; and freezing 2. A prevailing wind field must exist to bring HAIL them together Water droplets form in the cloud and get pushed upward, Frontolysis — dissipation/weakening of fronts where temperature are colder ○ One of the air masses overpowers the other Droplets freeze and form hailstones — grows as more ○ One: temperature difference between two air water droplets freeze on to them and eventually falls to masses disappears the ground ○ Two: the wind carries the air particles of the air ○ Created in thunderstorm clouds mass away from each other Has updraft that forms/collects the ice crystals into hail SLEET TYPES OF FRONTS By precipitation that forms when a thin layer of warmer 1. Warm Front air comes between layers of cold air Occurs when a warm air mass advances and Ice crystals > melts > water droplets > freezes sleet replaces a body of colder air (ice/snow) Diagonal movement Refrozen rain (closer to hail) More slowly, typically 10-25mph FREEZING RAIN The slope of the advancing front slides over the Like rain but it freezes as it touches the ground top of the cooler air and gradually pushes it out Ice crystals > melts > water droplets > freezes > during of the area landing (frozen water) Contains warm air that often has very high Not enough time to freeze when it drops that’s why it humidity freezes only when it touches the surface When warm air is lifted, temp. Drops, GRAUPEL condensation occurs Frosty kind of snow RESULT: usually produce quite a long period of Snow mixes with water (tiny) within clouds light and drizzly rain with a shorter spell of Forms below freezing temperatures when snow crystals heavier rain at the beginning of the front in the cloud collide with very cold water droplets Initial Heavy Rain, then light drizzling rain Water droplets freeze loosely on to the snow, giving As it advances, it eventually turns to cirrus graupel a slushy texture clouds (turns to ice crystals) Snowflakes that mixes with cold water Barometric pressure falls until the front passes SNOW Large amount of warm and cold air mixes, which Falls when all the air between the cloud and Earth’s eventually develops into cumulonimbus surface is below freezing IN FLIGHT ICING 2. Cold Front One of the most hazardous things that you can come by Occurs when a mass of cold, dense, and stable when you fly air advances and replaces a body of warmer air Slips under the warm front AIR MASS Horizontal movement Large body of air with daily uniform temperature and Moves more rapidly than warm fronts, 25-30mph, moisture content that can be up to 60mph 1. Continental Arctic - (cA) very cold & dry Faster because it’s heavier (has the power to lift 2. Continental Polar - (cP) cold & dry warm air) 3. Continental Tropical - (cT) hot, dry RESULT: Produces cumulus and cumulonimbus 4. Maritime Polar - (mP) cool, moist, unstable clouds that dominate the sky 5. Maritime Tropical - (mT) warm, moist, stable ○ Rain showers, lightning, hail (e.g., Philippines) ○ Cumulonimbus SOURCE REGIONS Like a frontal inversion An area where an air mass acquired the properties of ○ Cold moves to warm air temperature and moisture that determines its stability ○ Continuous Cumulonimbus clouds > An area in which the air remains relatively stagnant for a because of constant contact period of days/longer ○ Temperature 3. Stationary Front ○ Moisture Forms when two fronts meet up with each other FRONTS but no one wins. When an air mass moves out of its source regions, it Brings bad weather that may bring thunderstorm comes in contact with other air masses that have Neither warm or cold air mass is strong enough different temperature and moisture characteristics to take over the other/replace the other ○ Boundaries between air masses No movement/decrease of intensity of either Frontogenesis — creation of fronts fronts ○ Occurs when warm air converges onto colder air, Mostly equal intensity of both fronts and the horizontal temperature gradient Creates continuous updraft and creation of amplifies by at least an order of magnitude cumulonimbus clouds. ○ Conditions  RESULT: Long periods of rain, lines of STAGES: (Cells/Each stage may lasts for 45–60 minutes) thunderstorms ○ Cumulus Stage Bad weather for days Convective updraft forming the shape of the cloud 4. Occluded Front Water vapors are not heavy enough for it Warm front being overtaken by cold front which to bring rain could collide and be lifted by cooler air in front ○ Mature Stage Cold front lifts the warm front Accumulating Stage Produces very bad weather Updraft & downdraft – There’s also a Kinds: downdraft because air is getting colder, it Cold Front Occlusion needs to go down Cold front is first Cloud is already saturated Occurs when a fast-moving cold front is colder Thunder and lightning occurs than the air ahead of the slow-moving front ○ Dissipating Stage When the cold air mass overtaking the warm Cloud is shrinking front is colder than the cool air ahead of the Raining (downdrafts) are taming down warm front, and plows under both air masses. Cold front happening on top of warm front THUNDERSTORM HAZARDS Warm Front Occlusion SQUALL LINE Cool front first Narrow band of active thunderstorms The air ahead of the warm front is colder than the Ahead of a Cold front air of the cold from Cooler air lifts the cold front below the warm TORNADOES front Vortex formed by air drawn into a thunderstorm cloud When cool air mass overtaking the warm front is with initial rotating motion warmer than the cold air ahead of the warm front, and rides over the colder air mass while lifting TURBULENCE the warm air. Chaotic changes in pressure and flow velocity Warm front happening on top of another warm front ICING Happens when ambient temp reaches freezing and meets moisture Or temp of your aircraft is freezing temp and meets moisture Can form when: ○ There is water in liquid state ○ OAT is 0 deg C and below ○ Airframe temperature is 0 deg C and below Can lead to: Warm Front Occlusion Cold Front Occlusion ○ 30% reduction of lift ○ 40% increase in drag ** cold is cooler than cool ○ Increase in weight LIGHT Icing ○ Occasional use of de-ice required ○ Change of heading or altitude not required MODERATE ○ De-ice is necessary ○ Change of heading and altitude is desirable SEVERE ○ De-ice insufficient ○ Change of heading or altitude is necessary TYPES: THUNDERSTORMS ○ Rime – forms when small drops hit the aircraft One or more cumulonimbus clouds accompanied by and freeze rapidly. It usually looks like super thick sudden electrical discharge known as lighting frost. Milky white. Requirements: Moisture, unstable air mass, lifting action, ○ Clear — forms when large drops hit the aircraft and condensation nuclei and freeze slowly. Lasts from 30 to 60 minutes Characterized by cumulonimbus clouds, lighting, and CEILING AND VISIBILITY thunder Visibility nears zero within a thunderstorm cloud Conditions to form thunderstorms: Ceiling generally is close to the ground ○ Deep instability Effects on Altimeter ○ High moisture ○ Pressure drops rapidly with the approach of a ○ Trigger action thunderstorm  ○ Rises sharply with onset of first gust and arrival NEXRAD – Only 10 in the Philippines of heavy rain showers, Terminal Doppler Weather Radar (TWDR) ○ Falls back to normal as the storm moves on. (available in the Philippines) LIGHTNING Airport Surveillance Radar Electrical discharge Philippines: “Air Surveillance Radar” CLIMATOLOGY Inaugurated December 2023 Philippine Seasonal Weather and Winds Aircraft onboard radar 2 Seasons: Radius: 40-60 NM, 25,000 ft and Wet season below ○ June to October Satellite ○ Southwest monsoon (Habagat) ○ Satellite LIDAR — Light Detection and Ranging Dry season Measures wind speed, temperature, ○ November – February (cool dry season) water vapor, clouds, ○ March – May (hot dry season) SERVICE OUTLETS ○ Northeastern Monsoon (Amihan) Flight Service Station (FSS) BLUE– Type 1 ○ Primary source for preflight weather information (distinguished wet and dry | dry: november to april) ○ Mactan, Masbate, Dumaguete, Manila GREEN – Type 2 ○ Does not provide provide clearances (no dry season | heavy rain: november to april) ○ May also be available in uncontrolled RED – Type 3 aerodromes (seasons are not very pronounced, but still dry from Telephone Information Briefing Service (TIBS) november to april) ○ Recording of meteorological and aeronautical YELLOW – Type 4 information accessible through a touch tone only (where rainfall is evenly distributed throughout the year) Hazardous Inflight Weather Advisory Service (HIWAS) ○ VOR also (only in States) AVIATION WEATHER SERVICES ○ Automated continuous broadcast of weather Weather observation information through VORb Weather briefings (sourced from FSS) ○ Fully discontinued January 08 2020 Aviation weather reports (METAR, PIREP, etc.) Transcribed Weather Broadcast (TWEB) Aviation forecasts ○ Automated continuous broadcast of (Area Forecast, SIGMET, AirMET, TAF, etc.) meteorological and aeronautical data over Low, ATC radar weather displays (ATIS but focuses on specific Medium, and VHF NAVAIDS precipitation) ○ ATIS broadcasted through VORs Data Link Products (METAR, NEXRAD, Windy) ○ Fully discontinued January 01, 2020 (first: Service outlets Alaska) Weather charts (Surface analysis charts, PAGASA Charts, Prognostic Charts) WEATHER BRIEFINGS Provided by a specialist at an FSS WEATHER OBSERVATION Data given is dependent on your details and requested Surface Weather Aviation Observation briefing type ○ Observed weather at individual ground stations May request details of your flight (METAR) ○ Data sources can be automated (AWOS, ASOS) BRIEFING TYPE Manila MAY have this. Standard Briefing Meteorologists/PAGASA may also have ○ Provides the following information (if available) this Adverse conditions ○ Air Route Traffic Control Center (ARTCC) provides Current conditions separation for IFR traffic and can view Enroute forecast precipitation echoes on their radar displays Destination forecast Only detects local weather within the day Forecast winds and temperature aloft ○ YELLOW ALERT – lighting storm within 10 KM VFR flight not recommended ○ RED ALERT – lightning within 5 KM Synopsis ○ GREEN ALERT – 3 bursts of 5 seconds NOTAMS Upper Air Observation ATC Delay (EG: VFR closures ○ Weather gathered from the upper atmosphere Other information (radio frequencies) through Abbreviated Briefing Pilot observation (PIREPS) ○ Shortened version of a standard briefing and is Automated data collection (radiosondes) requested if departure is delayed 115,000 released yearly Outlook Briefing Radar Observation ○ A briefing to be requested if departure is more ○ Radio waves bouncing off of moisture in the air than 6 hours away ○ Color coded display according to precipitation ○ Expected contents are still same as Standard intensity WEATHER REPORT aggregated METAR information to assist in weather Qualifier forecasting. 1. Intensity or Proximity Codified observation message indicating an airfield ○ (–) Light weather conditions observed at a given time ○ Moderate (no qualifier) IMPORTANCE: Information with regards to departing and ○ (+) Heavy arriving aircrafts on what weather conditions can be ○ (VC) in the Vicinity expected in that specific aerodrome. 2. Descriptor Published every hour (unless no significant changes has ○ MI – Shallow been made) ○ BC — Patches SPECI – Special Report of Meteorological Conditions, ○ RD — Low drifting issued when one or more elements meet specified ○ BL — Blowing criteria significant to aviation ○ SH – Showers ○ Issued when there is significant deterioration or ○ TS — Thunderstorm improvement in airport weather conditions ○ FZ – Freezing ○ Unscheduled report due to the significant ○ PR — Partial change. Weather Phenomena 3. Precipitation PIREP — PILOT REPORT ○ DR — Drizzle Pilot reported weather observations ○ RA – Rain Pilots may file it with an FSS or ATC ○ SN — Snow Types of PIREP: Ice, Turbulence, Weather, ○ SG — Snow grains UA – Routine, UAA – Urgent ○ IC – Ice crystals (diamond dust) /OV – location of PIREP (+3 letter NAVAID identifier) ○ PL — Ice pellets /TM – Time PIREP was received from pilot ○ GR — Hail /FL – Flight level, altitude during report (hundred of ft) ○ GS — Small hail / snow pellets /TP – Type of aircraft ○ UP — Unknown precipitation /SK – Sky/Cloud coverage ○ Obscuration /WX – weather / flight visibility 4. Obscuration /TA – air temp ○ BR — Mist /WV – wind direction/velocity ○ FG — Fog /TB – Turbulence ○ FU — smoke /IC – Icing ○ DU — Dust ○ SA — Sand TAF — TERMINAL AERODROME FORECAST ○ HZ — Hze Forecast of weather conditions within 5 SM of a station ○ PY — Spray TAFs are published every 06 hours (4 times a day) valid ○ VA — Volcanic ash 24 hour time period (0000Z, 0600Z, 1200Z, 18000Z) 5. Other 5 Miles within the station ○ PO — Dust / Sand whirls NM vs miles vs SM ○ SQ — Squalls ○ SM – what you see in front of you ○ FC — Funnel cloud ○ NM – longitudes and latitudes, based on ○ +FC — Tornado or waterspout curvature of the Earth ○ SS — Sandstorm AVIATION FORECASTS ○ DS — Dust storm AREA FORECASTS (FA) ○ TL — “until” Gives a picture of clouds, general weather conditions, and visual meteorological conditions over a large area ** Others: Issued 3 times a day, valid for 18 hours (12-hr forecast, + PRESRR – pressure rising rapidly 6-hr outlook) PRESSFR – pressure falling Disseminated in four sections: TL – “until” ○ Header – source, date and time, validity, FM – “from” coverage AT – “at” ○ Precautionary Statements — IFR conditions, TM / TN – Max Temp / Min. Temp mountain obscurations, thunderstorm hazards P6SM – “plus 6 statute miles” or more than 6 SM visib ○ Synopsis – movement of pressure systems and Common weather abbreviation fronts ○ VFR Clouds and weather – sky conditions, WEATHER REPORTS visibility METAR — MET AERODROME REPORT Airman’s Meteorological Information AIRMET (WA) Meteorological Aerodrome Report (METAR) ○ Advisories given every 6 hours; intermediate Meteorological Terminal Aviation Routine Weather Report updates as needed / Meteorological Terminal Air Report / Meteorological Valid for the period of 6 hours until next Airfield Report regularly scheduled release (unless A METAR weather report is predominantly used by significant change is necessary/issued) aircraft pilots, and by meteorologists, who use  ○ Operational interest to all aircraft but weather phenomenon potentially hazardous to light aircraft Non-Convective Significant Meteorological Information SIGMET (WS) ○ Valid for 4 hours, or 6 hours if related to a hurricane ○ Advisories concerning non-convective weather (weather that is NOT caused by thunderstorms) potentially hazardous to all aircraft ○ Cover severe and extreme turbulence, severe icing, and widespread dust or sandstorms that reduce visibility to less than 3 miles. Convective Significant Meteorological Information (WST) ○ Advisories issued for hazardous convective weather hazardous to all flights ○ Routinely Issued at 55 minutes past the hour but can be issued any time in the interim as needed Remains valid for 2 hours ○ Issued for tornadoes, lines of thunderstorms, embedded thunderstorms of any intensity level, areas of thunderstorms greater than or equal to VIP level 4 with an area coverage of 4/10 (40%) or more, and hail 3/4 inch or greater. WINDS AND TEMPERATURE ALOFT FORECAST (FB) ○ Provides wind and temperature forecasts throughout specific locations ○ Computer-prepared forecasts of wind direction, wind speed, and temperature at specified times, altitudes, and locations ○ 3,000 to 39,000 ft. ○ Used primarily for FPP calculations Reported every 6 hours; 0600 UTC, 1200 UTC, 6 hours, of 12 Hrs validity SURFACE ANALYSIS CHART Depicts an analysis of the current surface weather, transmitted every 3 hours Depicts, pressure regions, fronts, temperature, dew points, wind direction and speed, local weather, and visual obscuration SFC to 1500 ft. WEATHER DEPICTION CHART Depicts surface conditions as derived from METAR and other surface observations Depicts cloud conditions and ceilings, fronts, local weather, and visual obscuration https://aviationweather.gov/gfa/#obs SIGNIFICANT WEATHER PROGNOSTIC CHART Depicts surface conditions as derived from METAR and other surface observations Depicts cloud conditions and ceilings, fronts, local weather, and visual obscuration PAGASA CHART, AWC Chart  READ AIRMET EXAMPLES INFLIGHT WEATHER ADVISORIES SIGMET (WS) YBBB SIGMET P02 VALID 240130/240730 YBRF-YBBB BRISBANE FIR TC ESTHER PSN S1642 E13842 CB OBS AT 0000Z WI 140NM OF TC CENTRE TOP FL600 MOV SSW 08KT WKN= AIRMET/SIGMET CODES FORECASTS VALIDITY ISSUED AREA VMC, clouds, Valid for 18 hours 3 times daily FORECASTS (FA) general WX (12 hours (issue time varies conditions over forecast + 6 by area) large area hours outlook) WINDS & TEMP wind direction, Valid for the 4 times daily ALOFT wind speed, and time/period FORECASTS (FB) temperature at stated specified times, altitudes, and locations AIRMET (WA) Relevant to all Valid for 6 Every 6 hours aircraft, hours/until next (0245 UTC) hazardous to issuance light SIGMET (WS) Non-convective 4 hours / 6 hours Unscheduled / WX, hazard to all (hurricane) issued only when non-convective SIGMET WX conditions exist SIGMET (WST) Convective WX, 2 hours 55 minutes past hazard to all the hour THREE (3) TYPES OF AIRMET AIRMET SIERRA (Mountain Obstruction) Issued for IFR conditions with ceilings of less than 1000’ and/or visibility of under 3 miles over at least 50% of the affected area. AIRMET Sierra can also be used to indicate mountain obstruction caused by low visibility Ceilings less than 1000 feet and/or visibility less than 3 miles affecting over 50% of the area at one time. Extensive mountain obscuration AIRMET TANGO (Turbulence) Issued when there is moderate turbulence, non-convective low-level wind shear, or sustained surface winds of 30 knots or more. Moderate turbulence Sustained surface winds of 30 knots or more at the surface AIRMET ZULU (Icing) Issued for moderate icing conditions and freezing levels. When an AIRMET Zulu is in place, there are freezing conditions in the area, so pilots should be alert for icing. Remember that airplane de-icing is a crucial step before you take off if you decide to fly in AIRMET Zulu Conditions. Moderate icing Freezing levels  No significant changes