Weather Theory Quiz Flashcards
Every physical process of weather is accompanied by, or is the result of, a
Heat Exchange
What causes variations in altimeter settings between weather reporting points?
Unequal heating of the earths surface.
A temperature inversion would most likely result in which weather condition?
An increase in temperature as altitude is increased.
One in-flight condition necessary for structural icing to form is
Visible Moisture
Why is frost considered hazardous to flight?
Frost spoils the smooth flow of air over the wings, decreasing lifting capabilities.
In what layer of the atmosphere does the majority of the weather occur?
Troposphere
All weather is caused by?
Unequal heating of the earth’s surface causing differences in pressure.
What are some causes of uneven heating of the Earth’s surface?
Tilted Earth, Pressure difference
How does air flow around high and low pressure in the northern hemisphere?
High - clockwise down and out
Low - counterclockwise, up and in
What effect causes the rotation of air around the high and low pressures?
Coriolis Force
What are isobars and what can they tell us about wind speed and velocity?
Line of constant pressure on a surface analysis chart, close lines = strong winds
What happens to air density as humidity increases?
Decreases
What is humidity?
Water vapor content in air.
What is a dew point?
The temperature to which air must be cooled to become saturated by water vapor already present in the air.
Define atmospheric stability.
The tendency of the atmosphere to resist upward movement
What is lapse rate?
Lapse rate is the decrease in temperature for the increase in altitude
What is the standard pressure and temperature for sea level?
29.92” HG, 15C
Would a 4° per thousand-foot lapse rate be considered stable or unstable air?
Unstable
Would warming from below increase or decrease stability?
Decrease
What are the characteristics of stable air?
Smooth, poor stability, continuous precipitation (if any), stratus clouds.
What are the characteristics of unstable air?
Turbulence, good visibility, showery precipitation (if any), cumulous clouds.
What would a cloud be called if it has extensive vertical development and precipitation?
Towering Cumulonimbus
What is an air mass?
Large area of air that is formed over a specific Earth region.
Would a warm front or a cold front be more stable and why?
A warm front would be more stable. This is because warmer air is less dense, making it rise above the cold air.
What is an occluded front?
When a cold front catches up to a warm front.
What is a stationary front.
When neither air mass is replacing the other.
What are the ingredients necessary for a thunderstorm to develop?
Moisture, Lifting force, unstable atmosphere.
What are the three stages of a thunderstorm?
Cumulous, mature, dissipating
What causes fog to form?
Fog forms when the temperature of the air near the ground is cooled to the air’s dew point.
What causes frost to form and why is it hazardous to aircraft?
When the dew point is reached, and the surface is below freezing, Frost spoils the smooth flow of air over the wings, thereby decreasing lifting capabilities.
