Oral Exam - Weather Flashcards
What are the general characteristics in regard to the flow of air around higha nd low pressure systems in the Northern Hemisphere?
Low pressure - inward, upward, and counterclockwise
High pressure - outward, downward, and clockwise
What is a trough?
An elongated area of relatively low atmospheric pressure
What is a ridge?
Elongated area of relatively high atmospheric pressure
What are the standard temperature and pressure values for sea level?
15 degrees celcius and 29.92”Hg
What are isobars?
A line on a weather chart which connects areas of equal or constant barometic pressure
What do the spacing of isobars on pressure charts indicate?
How steep or shallow a pressure gradient is
What causes winds aloft to flow parallel to the isobars?
Coriolois Force
Why do surface winds generally flow across the isobars at an angle?
Surface friction
At what rate does atmospheric pressure decrease with an increase in altitude?
1” Hg per 1,000 feet
What does dew point mean?
Dew point is the temperature to which a sample of air must be cooled to attain the state of saturation
When temp and dew point are close together, what weather is likely?
Visible moisutre in the form of clouds, dew, or fog.
What factor primarily determines the type and vertical extent of clouds?
Stability of the atmosphere
HOw do you determine the stability of the atmosphere?
By observing the actual lapse rate
List the effects of stable and unstalbe air on clouds, turbulence, precipitation, and visibility
Stable - Stratiform, smooth, steady, and fair to poor vis
Unstable - cumuliform, rough, showery, and good visibility
How to figure out where to expect bases of clouds?
Temp - dewpoint/4 X 1000 = base of clouds
What conditions are necessary for structural icing to occur?
Visibile moisture and below freezing temperatures at the point moisture strikes the aircraft?
What are two types of icing?
Structural and induction
Four types of structural ice?
Clear -
Rime -
Mixed -
Frost -
What to do if inadvertently encounter icing?
Change course and or altitude, climb to a higher altitude, if possible
What factors must be present for a thunderstorm to form?
Source of lift, unstable air, and high moisture content
Three stages of thunderstorm?
Cumulus, mature, dissipating
Temp inversion?
An inversion is an increase in temperature with height, a reversal of the normal decrease with height
Two basic way that fog may form
(1) Cool air to the dew point
(2) add moisture to the air
Name Several types of fog
Radiation, advection fog, upslope fog, precipitation indcued fog, ice fog
What causes radiation fog to form?
The ground cools the adjacent air to the dew point on calm, clear nights
What is advection fog and where is it most likely to form?
Advection fog results from the transport of warm humid air over a cold sufrace.
coastal areas during winter
What is upslope fog?
Result of moist, stable air being cooled adiabatically as it moves upsloping terrain.
Where is wind shear likely?
Low level temperature inversion
Wind shear in a frontal zone or thunderstorm
Clear air turbulence
Primary means by which to obtain a weather briefing?
Obtained from a breifer at the AFSS/FSS via 1800WXBRIEF
What are some examples of other sources of weather information? (5)
(1) Telephone information briefing services
(2) transcribed weather broadcasts (TWEB)
(3) Telephone Access to TWEB (TEL-TWB)
(4) Weather and aeronautical information from numerous private industry sources
(5) DUATS
Where can you find a listing of FSS and weather information numbers?
in the AFD or phonebook
What is EFAS?
En Route Flight Advisory Service is a service specifically designed to provide enroute aircraft with timely and meaning weather advisories pertinent to the type of flight intended, route, and altitude. Includes PIREPS
What is HIWAS?
continuous broadcast of inflight weather advisories including aviation weather warnings, SIGMETS, Convective SIGMETs, AIRMETS, PIREPS
What is a METAR?
an Aviation Routine Weather Report - hourly surface observations of conditions observed at an airport
What is a TAF
A Terminal Aerodrome Forecast is a consicise statement of the expected meteorological conditions within a 5 statue mile radius from the cetner of an airport’s runway complex during a 24 hours period
What is a convective SIGMET?
implies severe or greater turbulence sever icing and low level wind shear
SIGMET?
Advises of non-convective weather that is potentially hazardous to all aircraft
AIRMET?
Advisories of significant weather phenomena that describe conditions at intensities lower than those which require the issuance of SIGMETs intended for use by all pilot int he preflight and enroute phases of flight
What is a TWEB?
A transcribed weather broadcast - surface winds, visibility, weather, sky conditions, mountain obscurant, low level wind shear
What are Center Weather Advisories (CWA)
an aviation warning for use by aircrafts to anticpate and avoid adverse weather conditions in the en route and terminal environments
Convective Outlook?
A national forecast of thunderstorms, in 2 parts, Day 1 Convective outlook, and Day 2 Convective Outlook
What is IFR?
Ceilings less than 1,000 and or visibility less than 3 miles
what is MVFR?
Marginal VFR ceiling 1000 to 3000, and/or visibility 3-5 miles
VFR?
No ceiling, or ceiling greater than 3,000 and visibility greater than 5 miels
