Weather

What feature is associated with a temperature inversion?

A stable layer of air

What conditions are necessary for the formation of thunderstorms?

High humidity, lifting force, and unstable conditions

When warm, moist, stable air flows upslope, it

produces stratus type clouds

The presence of ice pellets at the surface is evidence that there

is a temperature inversion with freezing rain at a higher altitude

A nonfrontal, narrow band of active thunderstorms that often develop ahead of a cold front is known as a

squall line

What are characteristics of unstable air?

Turbulence and good surface visibility

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

friction between the wind and the surface

Clouds, fog, or dew will always form when

water vapor condenses

What clouds have the greatest turbulence?

Cumulonimbus

Clouds are divided into four families according to their

height range

Steady precipitation preceding a front is an indication of

stratiform clouds with little or no turbulence

Upon encountering severe turbulence, which flight condition should the pilot attempt to maintain?

Level flight attitude

What are characteristics of a moist, unstable air mass?

Cumuliform clouds and showery precipitation

What weather phenomenon is always associated with thunderstorm?

Lightning

The amount of water vapor which air can hold depends on

air temperature

How will frost on the wings of an airplane affect takeoff performance?

Frost will disrupt the smooth flow of air over the wing, adversely affecting its lifting capability

What causes variations in altimeter setting between weather reporting points?

Unequal heating of the Earth’s surface

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

Clouds with considerable vertical development and associated turbulence

Thunderstorms which generally produce the most intense hazard to aircraft are

squall line thunderstorms

Possible mountain wave turbulence could be anticipated when winds of 40 knots or greater blow

across a mountain range, and the air is stable

What feature is normally associated with the cumulus stage of thunderstorm?

Continuous updraft

When may hazardous wind shear be expected?

In areas of low-level temperature inversion, frontal zones, and clear air turbulence

If the temperature/dew point spread is small and decreasing, and the temperature is 62 degrees F, what type weather is most likely to develop?

Fog or low clouds

The mature stage of a thunderstorm begins with

the start of precipitation

Thunderstorms reach their greatest intensity during the

mature stage

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

heat exchange

What type of fog depend upon wind in order to exist?

Advection fog and upslope fog

Why is frost considered hazardous to flight?

Frost spoils the smooth flow of air over the wings, thereby decreasing lifting capability

One of the most easily recognized discontinuities across a front is

a change in temperature

What 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

The conditions necessary for the formation of cumulonimbus clouds are a lifting action and

unstable, moist air

The suffix ‘nimbus,’ used in naming clouds, means

a rain cloud

If there is thunderstorm activity in the vicinity of an airport at which you plan to land, which hazardous atmospheric phenomenon might be expected on the landing approach?

Wind shear turbulence

How does frost effect the lifting surfaces of an airplane on takeoff?

Frost may prevent the airplane from becoming airborne at normal takeoff speed

What is meant by the term dew point?

The temperature at which air must be cooled to become saturated

Convective circulation patterns associated with sea breezes are caused by

cool, dense air moving inland from over the water

When there is a temperature inversion, you would expect to experience

an increase in temperature as altitude increases

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

What would decrease the stability of an air mass?

Warming from below

What weather phenomenon signals the beginning of the mature stage of a thunderstorm?

Precipitation beginning to fall

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

Actual lapse rate

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

Poor surface visibility

What is a characteristic of stable air?

Stratiform clouds

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

In what situation is advection fog most likely to form?

An air mass moving inland from the coast in winter

What cloud types would indicate convective turbulence?

Towering cumulus clouds

Low-level turbulence can occur and icing can become hazardous in what type of fog?

Steam fog

Where does wind shear occur

At all altitudes, in all directions

A pilot can expect a wind shear zone in a temperature inversion whenever the windspeed at 2,000 to 4,000 feet above the surface is at least

25 knotts

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

Evaporation and sublimation

What situation is most conductive to the formation of radiation fog?

Warm, moist air over low, flatland areas on clear, clam nights

During the life cycle of a thunderstorm, which stage is characterized predominantly by downdrafts?

Dissipating

One inflight condition necessary for structural icing to form is

visible moisture

What condition result in the formation of frost?

The temperature of the collecting surface is at or below the dew point of the adjacent air and the dew point is below freezing

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

wind direction

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

standing lenticular clouds