Flashcards
What are the primary components of the Earth’s atmosphere?
Oxygen 21%, Nitrogen 78%, and 1% trace gases.
What is the tropopause and how does its altitude vary?
The tropopause is the boundary between the troposphere and the stratosphere.
It is at 26,000ft/8km with -50°C at the Poles and at 60,000ft/18km with -75°C at the Equator.
The ISA tropopause is always at 36,090ft/11km with -56.5°C.
What is the International Standard Atmosphere (ISA) temperature lapse rate?
The ISA temperature lapse rate is 1.98°C/1000ft or 0.65°C/100m up to a height of 11km/36,090ft.
How does atmospheric pressure change with altitude according to the ISA?
At the surface: 1013.25hPa,
at 18,000ft: 500hPa,
at 30,000ft: 300hPa,
and at 38,000ft: 200hPa.
What is the Stevenson’s screen used for?
It houses wet and dry thermometers and is placed about 4’ above the surface to measure temperature.
What causes diurnal variation of temperature?
The hottest time of day is 2 hours after local noon and the coldest is 30 minutes after sunrise.
Cloud cover or wind can reduce the temperature range.
What are the different types of pressure systems?
Low Pressure/Depression, High Pressure/Anti-cyclone, Trough of Low Pressure, Ridge of High Pressure, and Col.
How does density altitude affect aircraft performance?
Higher temperature (low density), high altitude (low pressure), and high humidity decrease density, affecting aircraft performance, especially takeoff roll.
What is the role of latent heat in atmospheric processes?
Condensation and freezing release latent heat (warming the atmosphere),
while evaporation and melting absorb latent heat (cooling the atmosphere).
What are the characteristics of unstable atmospheric conditions?
Unstable conditions are associated with cumuliform clouds, showers, good visibility, and moderate to severe turbulence.
What cloud types are associated with significant icing risks?
High risk: cumuliform clouds (Cu, Cb) in temperatures 0°C to -20°C.
Moderate risk: stratiform clouds (Ns, Cu, Cb) with large supercooled water droplets.
What are the three main cloud shapes?
Cirriform (wispy), Stratiform (layer), and Cumuliform (lumpy).
What is the Bergeron-Findeisen theory?
It states that all precipitation starts as ice crystals, growing through sublimation in supercooled water droplets.
What are the phases of a thunderstorm?
Building phase (updrafts only, 20 minutes),
mature phase (updrafts and downdrafts, 20 minutes),
and dissipating phase (downdrafts only, 1.5 to 2.5 hours).
What are the primary hazards associated with thunderstorms?
Microbursts, gust fronts, turbulence, wind shear, icing, hail, tornadoes, water ingestion, virga, lightning, static, and instrument error.
What are the three major atmospheric circulation cells?
The three major atmospheric circulation cells are the Hadley Cell, the Ferrel Cell, and the Polar Cell.
What causes the Coriolis Effect?
The Coriolis Effect is caused by the rotation of the Earth, which deflects the path of moving air and water to the RIGHT in the Northern Hemisphere and to the LEFT in the Southern Hemisphere.
What are katabatic winds?
Cold downslope winds that typically occur at night and can lead to the development of mountain winds flowing out of valleys during the night.
Give an example of a katabatic wind.
The Bora wind in the Adriatic, which can reach speeds of 70-100 kts.
What is the Dry Adiabatic Lapse Rate (DALR)?
3°C per 1000 feet or 1°C per 100 meters.
What is relative humidity?
The percentage of water vapor present in the air compared to the amount needed for saturation at the same temperature.
What happens when air reaches its dew point temperature?
The air becomes saturated, and water vapor condenses into liquid.
Define dew point.
The temperature to which air must be cooled to become saturated.
What is a temperature inversion?
A situation where temperature increases with altitude, trapping pollutants and leading to poor air quality.
