Weather & Aviation Weather Sources Flashcards
What is the sudden, drastic change in wind that can happen at any altitude?
Wind Shear
What is the effect on engine performance in high density altitudes?
Decreased efficiency
What is the effect on engine performance during low density altitudes?
Increased efficiency
What are the three life cycles of a thunderstorm?
Cumulus, Mature, Dissipating
Which thunderstorm life cycle is characterized by downdrafts?
Dissipating
High wispy clouds
Stratus
What can be caused by an aircraft flying through visible water such as rain or cloud droplets and the temperature where the moisture strikes the aircraft is 0 degrees Celsius?
Structural Icing
What is the zone between two different air masses where temperature, humidity, and wind can change over short distances?
Front
What is a sudden, drastic change in wind speed and/or direction over a very small area?
Wind Shear
What is the routine observation of current surface weather reported in a standard international format?
METAR
Name two weather sources that play a major role in gathering surface observations.
ASOS & AWOS
What is the altitude in the standard atmosphere that corresponds to a particular value of air density?
Density Altitude
What effect does air density have on density altitudes?
Decrease in air density = high density altitude
Increase in air density = low density altitude
Thin air refers to what density altitude?
High Density Altitude
Dense air refers to what density altitude?
Low Density Altitude
What density altitude is caused by high elevations, low atmospheric pressures, high temperatures, high humidity, or some combination of these factors?
High Density Altitudes
What density altitude is caused by lower elevations, high atmospheric pressure, low temperatures, low humidity, or a combination of these factors?
Low Density Altitude
What proportionally relates to density so that when it is doubled or lowered, so is the density?
Pressure
What effect does increasing and decreasing temperatures have on density?
Increasing temperature decreases its density, decreasing temperature increases its density.
In the atmosphere, both temperature and pressure decrease with altitude and have conflicting effects upon density. However, the fairly rapid drop in pressure as altitude is increased usually has the dominant effect. What can the pilot expect the density to do with altitude?
Density decreases with altitude.
What is the amount of water vapor contained in the atmosphere expressed as a percentage of the maximum amount of water vapor the air can hold?
Humidity (relative humidity)
What effect does weight have on aircraft performance?
Climb performance diminishes with altitude
What is standard sea level pressure is defined as?
29.92”Hg and a standard temperature of 59 degrees F (15 degrees) C
What can break up the flow of wind and create wind gusts that change rapidly in direction, causing turbulence?
Ground topography and large buildings
While wind shear can occur at any altitude, why is low-level wind shear especially dangerous to aircraft?
Due to the proximity of an aircraft to the ground
What is the most severe type of low-level wind shear associated with convective precipitation into dry air at cloud base?
Microburst
What is the atmosphere’s ability to resist vertical motion?
Atmospheric Stability
How does a stable and unstable atmosphere effect vertical movements?
Stable atmospheres make vertical movement difficult while unstable atmospheres tend to make vertical movements larger
What atmospheric stability can lead to significant turbulence, extensive vertical clouds, and severe weather?
Unstable
What atmospheric pressure is characterized by cool, dry air that resists vertical movement and leads to good and generally clear weather?
Stable
What atmospheric stability is characterized by moist and warm air that typically causes thunderstorms to form?
Unstable
What temperature inversion is caused by air that is close to the ground being cooled by the lowering temperature of the ground, typically on clear, cool nights?
Surface Based Temperature Inversion
What temperature inversion occurs when warm air spreads over a layer of cooler air or cooler air is forced under a layer of warmer air?
Frontal Temperature Inversion
What is the temperature at which the air can hold no more moisture, given in degrees?
Dew Point
What is the most dangerous cloud type to pilots?
Cumulonimbus Clouds, particularly squall lines
What cloud type is formed on the crest of waves created by barriers in the wind flow that show little movement with smooth and polished edges, but are a good indication of very strong turbulence and should be avoided.
Standing Lenticular Altocumulus Clouds
What type of air mass stability is characterized by the following?
- Cumuliform Clouds
- Showery Precipitation
- Rough and Turbulent Air
- Good Visibility (except in blowing obstructions)
Unstable Air
What type of air mass stability is characterized by the following?
- Stratiform clouds and fog
- Smooth air
- Fair to poor visibility in haze and smoke
- Continuous Precipitation
Stable Air
Which thunderstorm lifecycle stage is characterized by updrafts with rapid upward growth?
Cumulus
Which thunderstorm lifecycle stage is signaled by precipitation beginning to fall?
Mature
What is the lowest layer of clouds called?
Cloud Ceiling
What altitude is the height above ground level?
Absolute Altitude
What altitude is the height above mean sea level?
True Altitude
What is a standard day?
Where temperature is 15 degrees C (59 degrees F), barometric pressure is 29,92Hg, and pressure altitude is equal to density altitude
Moisture is added to air by what?
Evaporation and sublimation
