A heat exchange
The movement of air
A pressure differential
Sublimation and condensation
Evaporation and condensation
Evaporation and sublimation
Close together, the pressure gradient force is slight and wind velocities are weaker
Not close together, the pressure gradient force is greater and wind velocities are stronger.
Close together, the pressure gradient force is greater and wind velocities are stronger.
The earth's rotation
Air mass modification
Is colder than the air behind the overtaking cold front.
Is warmer than the air behind the overtaking cold front.
Has the same temperature as the air behind the overtaking cold front.
A high-pressure area or ridge is an area of rising air.
A high-pressure area or trough is an area descending air.
A high-pressure area or ridge is an area of descending air.
Pressure gradient force
Dust or haze at flight level
Long streaks of cirrus clouds
A constant outside air temperature
Constant height above the Earth
Abrupt change in temperature lapse rate.
Absolute upper limit of cloud formation
15°C and 29.92" Hg
59°F and 1013.2" Hg
15°C and 19.92" Mb
Decreases as the relative humidity decreases.
Decreases as the relative humidity increases.
Increases as the relative humidity increases
Stable, moist air and orographic lifting
Unstable, moist air and orographic lifting
Unstable, moist air and no lifting mechanism
Cumiliform clouds, turbulence, and poor visibility.
Cumiliform clouds, turbulence, and good visibility.
Stratiform clouds, smooth air and poor visibility.
Evaporation of precipitation
Good visibility, steady precipitation, stratus clouds
Poor visibility, steady precipitation, stratus clouds
Poor visibility, intermittent precipitation, cumulus clouds
Warming from below
Cooling from below
Decrease in water vapor
Poor visibility and smooth air
Cumiliform clouds and showery precipitation
Stratiform clouds and continuous precipitation
The ambient lapse rate
The dry adiabatic rate
Base of the clouds near the surface, heavy rain and hail.
Low ceiling and visibility, hail and precipitation static.
Cumulonimbus clouds, very frequent lightning and roll clouds
Beginning of rain at the surface
They form slowly, but move rapidly.
They are associated with frontal system only
They offer the most intense weather hazards to aircraft
Updrafts continue to develop throughout the dissipating stage of a thunderstorm.
The beginning of rain at the Earth's surface indicates the mature stage of the thunderstorm.
The beginning of rain at the Earth's surface indicates the dissipating stage of the thunderstorm.
The start of rain
The appearance of an anvil top
Growth rate of cloud is maximum