FAA Private Pilot Exam: Weather Theory

At approximately what altitude above the surface would the pilot expect the base of cumuliform clouds if the surface air temperature is 82 °F and the dewpoint is 38 °F?

10,000 feet AGL.

What are the standard temperature and pressure values for sea level?

15 °C and 29.92 inches Hg.

The standard temperature lapse rate is:

2°C per 1,000 feet.

What is the approximate base of the cumulus clouds if the surface air temperature at 1,000 feet MSL is 70 °F and the dewpoint is 48 °F?

6,000 feet MSL.

If you will be flying with cumulus clouds, you might expect:

A bumpy flight with good visibility.

Wind shear can be defined as:

A change in wind direction or wind speed.

Which is true with respect to a high - or low-pressure system?

A high-pressure area or ridge is an area of descending air.

What feature is associated with a temperature inversion?

A stable layer of air.

What measurement can be used to determine the stability of the atmosphere?

Actual lapse rate.

A temperature inversion would most likely result in which weather condition?

An increase in temperature as altitude is increased.

You can expect dangerous turbulence in mountain waves and:

Below rotor clouds.

If an unstable air mass is forced upward, what type clouds can be expected?

Clouds with considerable vertical development and associated turbulence.

What causes sea breezes to move inland?

Cool, dense air moving inland from over the water to replace warm air that has risen over the land.

What are characteristics of a moist, unstable air mass?

Cumuliform clouds and showery precipitation.

The life cycle of a thunderstorm cell has distinct three stages:

Cumulus stage, mature stage, and dissipating stage.

What are the processes by which moisture is added to unsaturated air?

Evaporation and sublimation.

Humid air at the surface, especially in summer, can cause:

Instability and the formation of afternoon thunderstorms

A stable air mass is most likely to have which characteristic?

Poor surface visibility.

Low level inversions may cause:

Smoke and dust to be trapped close to the surface.

Which weather conditions should be expected beneath a low-level temperature inversion layer when the relative humidity is high?

Smooth air, poor visibility, fog, haze, or low clouds.

Steady precipitation preceding a front is an indication of

Strati-form clouds with little or no turbulence

What is a characteristic of stable air?

Stratiform clouds.

What atmospheric layer is typified by a relatively small change in temperature?

Stratosphere

Layered clouds are called:

Stratus.

Which conditions result in the formation of frost?

The temperature of the collecting surface is at or below the dewpoint of the adjacent air and the dewpoint is below freezing.

What is meant by the term 'dewpoint'?

The temperature to which air must be cooled to become saturated.

The layers of the atmosphere, beginning at the earths surface, are:

Troposphere, Stratosphere, and Mesosphere

What are characteristics of unstable air?

Turbulence and good surface visibility.

What causes variations in altimeter settings between weather reporting points?

Unequal heating of the Earth's surface.

There are three conditions necessary to create thunderstorms. They are:

Unstable air, high moisture content, and a source of lift.

What would decrease the stability of an air mass?

Warming from below.

After takeoff you encounter a temperature inversion. You should expect:

Wind shear.

One of the most easily recognized discontinuities across a front is

a change in temperature.

An almond or lens-shaped cloud which appears stationary, but which may contain winds of 50 knots or more, is referred to as

a lenticular cloud.

The suffix 'nimbus,' used in naming clouds, means

a rain cloud.

The amount of water vapor which air can hold depends on the

air temperature.

The wind at 5,000 feet AGL is southwesterly while the surface wind is southerly. This difference in direction is primarily due to

friction between the wind and the surface.

The boundary between two different air masses is referred to as a

front.

Every physical process of weather is accompanied by, or is the result of, a

heat exchange.

Clouds are divided into four families according to their

height range.

Moist, stable air flowing up-slope can be expected to

produce stratus type clouds.

Crests of standing mountain waves may be marked by stationary, lens-shaped clouds known as

standing lenticular clouds.

'Steady precipitation preceding a front is an indication of

stratiform clouds with little or no turbulence.

The most frequent type of ground or surface-based temperature inversion is that which is produced by

terrestrial radiation on a clear, relatively still night.

Clouds, fog, or dew will always form when

water vapor condenses.

One weather phenomenon which will always occur when flying across a front is a change in the

wind direction.