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43 Cards in this Set
- Front
- Back
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What rate does atmospheric pressure decrease with an increase in altitude?
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1" per 1000'
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What are standard temperature and pressure values for sea level?
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15c and 29.92 Hg std at sea level
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Characteristics of high and low pressure systems in the northern hemisphere?
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Low pressure-air flows inward, upward and counterclockwise
High pressure-air flows outward downward and clockwise |
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What causes the winds aloft to flow parallel to the isobars?
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Coriolis force: isobars and surface winds flow across isobars because of surface friction
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When temp and dewpoint are close (within 5º) what kind of weather is likely?
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Visible moisture, clouds , dew or fog
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What determines the vertical extent of clouds?
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Stability of the atmosphere
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Difference between stable and unstable?
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Unstable: air is displaced vertically
Stable: air resist vertical movement |
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The effects of stable and unstable air on clouds, turbulence, precipitation and visibility:
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Stable Unstable
Clouds: Stratiform Cumuliform Turbulence Smooth Rough Precip Steady Showery Visibility Fair to Poor Good |
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Two types of icing?
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Structural and induction
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Four types of structural icing?
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Clear - large drops strike the surface and freeze slowly
Rime - small drops hit the surface and freeze quick Mixed - combination of clear and rime supercooled varying in size Frost - ice crystal deposits formed when the temp and dew point are below freezing |
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What conditions are necessary for structural icing?
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Visible moisture and below freezing when it strikes the surface
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Which type is more dangerous?
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Clear ice…freezes to a solid sheet of ice/\.
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What factors must be present for a thunderstorm to form?
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Source of lift (heat or fast moving front
Unstable air High moisture ( temp and dew close) |
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What are "squall line thunderstorms"?
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Narrow band of thunderstorms…often infront of a cold front in moist unstable air.
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Basic ways fog forms?
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Cooling air to the dew point, adding moisture to the air
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Types of fog?
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Radiation, Advection, Upslope, Precip induced and Ice
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What causes radiation fog?
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Clear sky, small temp and dew spread, normally at daybreak and night.
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What causes advection fog?
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Coastal areas, moist air over colder ground.
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Upslope fog?
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Moves up sloping terrain, common east of the Appalachians.
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Ice fog?
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Usually -25ºF sublimates from ice crystals…Artic regions.
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Precip fog?
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Warm rain through cool air…normally associated with warm fronts
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Other than fog what are other IFR weather producers?
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Low clouds, smoke, haze, precip….
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Primary means of obtaining weather briefing?
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Weather briefer
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Sources of weather info?
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Telephone AFSS
TWEB Internet private sources DUATS AOPA |
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What should a briefing include?
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Adverse conditions, VFR not recommended, synopsis, current conditions, enrout forecast, destination forecast, winds aloft, NOTAMS, ATC delay.
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What is EFAS?
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Enroute Flight Advisory Service…from 5000 to 17,500' AGL on 122.0
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What is HIWAS?
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Hazardous in-flight weather advisory on a continuous broadcast…byp vor
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What is is a METAR
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A routine weather report…a weather observers interpretation.
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Read this:
METAR KLAX 140651Z AUTO 0000K 1SM R35L/4500V600FT-RA BR BKN030 10/10 A2990 RMK AO2 |
LA zero six five one observation, wind calm, visibility one, runway 35 left RVR
variable between 4500' & 6000', light rain,mist, broken ceiling 3000', temp 10, dew point 10, altimeter 2990 |
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Automated Surface Observations?
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ASOS: Automated Surface Observing…primary US surface weather observing system…
METAR NAVAID AWOS |
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What are PIREPs?
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Pilot weather reports. Required elements are type of report, location, time, flight level MSL, aircraft type
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Distance for visibility is reported in?
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SM; all others in NM.
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What are radar weather reports (SD's)
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General areas of precip, rain, snow, thunderstorms observed by radar, includes intensity, location of the echo top.
heights are MSL reported H+35. SD's should be used with METARS, satellite photos when flight planning…once airborne depend on Flight Watch |
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What are TAFs
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Terminal Aerodrome Forecast…within 5 SM radius from the center of the airport
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What is Aviation Area Forecast FA's ?
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A forecast of visual meteorological conditions VMC. Clouds and general weather conditions over several states.
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What is a convective SIGMET?
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Severe thunderstorm, winds 50kts or greater, hail 3/4 or bigger, tornadoes, embedded thunderstorms, line of thunderstorms, heavy rains
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What is a SIGMET?
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Non-convective potentially hazardous, sever icing, turbulence, dust or sand storms visibilities less than 3 miles Volcanic ash. Not associated with thunderstorms
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What is an AIRMET?
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Lower than SIGMET, mountain obscuration, turbulence, strong surface winds, icing.
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What is a TWEB?
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Local forecast of 50 nm. winds 25 kts or greater ceiling/cloud heights, mountain obscurement, low level wind shear.
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What info can be determined by temp and winds aloft forecast?
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Favorable altitude based on wind direction and speed. Areas of icing, Temp inversions, Turbulence…abrupt change in wind direction.
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What is a Center Weather Advisory CWA?
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Warning to anticipate and avoid adverse weather.
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What is a Convective Outlook AC?
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Planning tool to avoid areas of high, moderate, slight risk of thunderstorms.
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Some examples of weather charts?
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Surface Analysis Transmitted every 3 Hrs, good for locating pressure systems and fronts
Radar Summary Hourly, displays precip, intensity, coverage, echo tops, cell movement, doesn't show clouds or fog Significant Weather Prog Forecast for weather 12-24-36-48 hours…surface fronts, squall lines Winds and Temp Aloft Convective Outlook. |
