Weather Theory Flashcards
What effect, if any, does high humidity have on aircraft performance?
It decreases performance.
What effect does high density altitude, as compared to low density altitude, have on propeller efficiency and why?
Efficiency is reduced because the propeller exerts less force at high density altitudes than at low density altitudes.
Every physical process of weather is accompanied by, or is the result of, a
heat exchange.
The sun (or heat exchange) is the primary reason for every physical process of weather on the planet. Watch the “Circulation Pattern” video for more information.
Which of the following considerations is more relevant to a Remote PIC when evaluating unmanned aircraft performance?
Current weather conditions.
How would high density altitude affect the performance of a small unmanned aircraft?
Decreased performance.
What effect does high density altitude have on the efficiency of a UA propeller?
Propeller efficiency is decreased.
What are the standard temperature and pressure values for sea level?
15°C and 29.92” Hg.
Which combination of atmospheric conditions will reduce aircraft takeoff and climb performance?
High temperature, high relative humidity, and high density altitude.
You are flying near mountains, and there are lenticular clouds. What kind of weather should you expect?
very rough air/turbulence.
The amount of water vapor which air can hold depends on the
air temperature.
What clouds have the greatest turbulence?
Cumulonimbus.
The suffix “nimbus,” used in naming clouds, means
a rain cloud.
Convective circulation patterns associated with sea breezes are caused by
cool, dense air moving inland from over the water.
Low-level turbulence can occur and icing can become hazardous in which type of fog?
Steam fog.
While operating around buildings, the Remote Pilot in Command should be aware of the creation of wind gusts that
change rapidly in direction and speed causing turbulence.
What situation is most conducive to the formation of radiation fog?
Warm, moist air over low, flatland areas on clear, calm nights.
In which situation is advection fog most likely to form?
An air mass moving inland from the coast in winter.
What types of fog depend upon wind in order to exist?
Advection fog and upslope fog.
What is meant by the term “dewpoint”?
The temperature to which air must be cooled to become saturated.
What cloud types would indicate convective turbulence?
Towering cumulus clouds.
An air mass moving inland from the coast in winter is likely to result in
fog.
What situation is most conducive to the formation of radiation fog?
Warm, moist air over low, flatland areas on clear, calm nights.
What conditions are necessary for the formation of thunderstorms?
High humidity, lifting force, and unstable conditions.
A stable air mass is most likely to have which characteristic?
Poor surface visibility.
One of the most easily recognized discontinuities across a front is
a change in temperature.
The boundary between two different air masses is referred to as a
front.
The conditions necessary for the formation of cumulonimbus clouds are a lifting action and
unstable, moist air.
One in-flight condition necessary for structural icing to form is
visible moisture.
What is a characteristic of stable air?
Stratiform clouds.
In which environment is aircraft structural ice most likely to have the highest accumulation rate?
Freezing rain.
What are characteristics of a moist, unstable air mass?
Turbulence and showery precipitation.
What are the characteristics of stable air?
Poor visibility and steady precipitation.
During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts?
Dissipating.
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.
One weather phenomenon which will always occur when flying across a front is a change in the
wind direction.
Thunderstorms reach their greatest intensity during the
mature stage.
Which weather phenomenon signals the beginning of the mature stage of a thunderstorm?
Precipitation beginning to fall.
Which weather phenomenon is always associated with a thunderstorm?
Lightning.
What are characteristics of unstable air?
Turbulence and good surface visibility.
What feature is normally associated with the cumulus stage of a thunderstorm?
Continuous updraft.
