Aviation Weather Flashcards
Six basic elements of weather are the following:
- Temperature (warm or cold).
- Pressure.
- Wind (a vector with speed and direction).
- Moisture (or humidity).
- Clouds.
- Precipitation.
What is the composition percentage of dry air?
78% Nitrogen
21% Oxygen
1% Other Gases
What two additional ingredients does natural air have that dry air does not?
Condensation nuclei
Water vapor
Between the 30°- 60°N latitude is primarily where the U.S. is located. What is the prevailing wind
direction?
From the West
In which layer of the atmosphere does weather occur?
Troposphere
What is a cP?
c: Continental Air Mass (Dry Air)
P:Polar Air Mass (40-60)
(cold dry)
What are the characteristics of a cP?
Cold, dry air moving from the polar regions generally in southeast direction
Explain the difference between convection and advection.
Convection is the transfer of heat by way of gas (VERTICAL exchange of heat energy)
Advection is the HORIZONTAL transfer of heat by wind. (transfer of heat is greater than vertical transfer of heat)
In late evening, a thick layer of clouds have moved over your airfield.
WIll a (radiation) nocturnal inversion happen this evening? Why or why not?
No, the clouds will prevent an inversion from happening by keeping the warmer air near the surface
Define sea level pressure in two units of measurement.
29.92”
Hg (Inches of mercury)
1013.2
mb (millibars) or hP (hectopascals)
How is change in pressure depicted on a weather chart?
Isobars: Lines connecting points of equal pressure corrected to sea level, usually spaced 4mb apart.
What determines wind speed?
Pressure Gradient Force (PGF): Force exerted by a change in pressure per unit of horizontal distance.
Describe the wind speed at Location A and B.
Location A is strong winds
Location B is light winds
Isobars closely spaced – strong or steep pressure gradient, moderate to strong wind
Isobars widely spaced – weak or flat pressure gradient, calm or light wind
You’re on a true course of 010° and wind is from 280°. What type of weather conditions
should you expect?
Moving toward low pressure, lifting air, vertical clouds, turbulence, and possible storms.
Buys Ballot’ Law: Standing with your back to the wind, the low pressure will be to your __________________. Flying with a tailwind, the low pressure is on the _______ side of the aircraft.
Buys Ballot’ Law: Standing with your back to the wind, the low pressure will be to your left (Northern Hemisphere). Flying with a tailwind, the low pressure is on the left side of the aircraft.
(Classroom Left low door, right high door)
You’re departing Denver with an altimeter setting of 30.22. You arrive at New Orleans with an
altimeter setting of 30.00. You failed to reset your altimeter. Is your true altitude higher or lower than indicated?
Lower
How is flight performance affected by moisture in the atmosphere?
Less air density = higher density altitude = reduction in lift and reduction in engine performance
Which 3 atmospheric conditions provide for best lift?
High pressure
Low temperature
Low humidity
What kind of cloud would you expect at low altitude in unstable environment?
Cumuliform Clouds (Horizontal)
-Showery Precipitation
-Rough Air, Turbulence
-Good Visibility
What kind of cloud would you expect at low altitude in a stable environment?
Stratiform Clouds and Fog (Vertical)
-Continuous Precipitation
-Smooth Air
-Fair to Poor Visibility
During stagefield training and frontal passage, what would you expect to happen to wind
direction and speed?
What happens as warm air is lifted over a cold air mass?
Over the past several hours the altimeter setting at KOZR has been decreasing. Now, after
listening to ATIS, you notice the setting has increased. The wind is now blowing from the
NW and the OAT is showing a lower temperature. What has happened at KOZR?
Abbreviations or the following Low Level Cloud Bases within 6500’ AGL
Cumulus:
Stratus:
Stratocumulus:
Cumulonimbus:
Cumulus: CU
Stratus: ST
Stratocumulus: SC
Cumulonimbus: CB