Key Questions Flashcards
(148 cards)
Changes or variations of weather patterns are caused by:
the unequal heating of the earths surface
Warmer air has as tendency to:
Rise (low pressure)
Colder air has the tendency to:
settle or descend (high pressure) and replace rising warmer air
Coriolis force
deflects wind to the right at higher altitudes as it rises (in northern hemisphere)
What causes variations in altimeter settings between weather reporting points?
Unequal heating of the earth’s surface
Development of thermals depends on:
solar heating (thermals are updrafts in convective currents dependent on solar heating)
The general circulation and wind rules in the Northern Hemisphere are as follows:
- Air circulates in a clockwise direction around a high
- Air circulates in a counterclockwise direction around a low
- The closer the isobars are together, the stronger the wind speed
- Due to surface friction (up to about 2,000ft AGL), surface winds do not exactly parallel the isobars , but move outward from the center of the high toward lower pressure
Convective circulation patterns associated with sea breezes are caused by:
cool, dense air moving inland from over the water
What is the proper airspeed to use when flying between thermals on a cross-country flight against a headwind?
The best lift/drag speed increased by one-half the estimated wind velocity.
When gliding into a headwind, maximum distance will be achieved by adding approximately one-half the estimated headwind velocity to the best L/D speed.
Standard Temperature (sea level)
59°F (15°C)
Standard Lapse Rate (Temperature)
2°C (3.5°F) per 1,000 feet
When there is a temperature inversion, you would expect to experience:
an increase in temperature as altitude increases
A ground-based inversion usually means poor visibility
Relative Humidity
relates the actual water vapor present in the air to that which could be present in the air. Temperature largely determines the max amount of water vapor air can hold. Warm air can hold more water vapor than cold air
Dew Point
The temperature to which air must be cooled to become saturated by the water already present in the air
Clouds, fog, or dew will always form when:
water vapor condenses
What are the processes by which moisture is added to unsaturated air?
Evaporation and sublimation
Ridge
elongated area of high pressure
Trough
elongated area of low pressure. All fronts lie in troughs
Cold Front
leading edge of an advancing cold air mass
Warm Front
leading edge of an advancing warm air mass. Warm fronts move about half as fast as cold fronts.
Frontal Waves and Cyclones (areas of low pressure)
usually form on slow-moving cold fronts or stationary fronts
Frontal Passage will be indicated by the following discontinuities:
- A temperature change (most easily recognizable)
- A continuous decrease in pressure followed by and increase as the front passes
- A shift in the wind direction, speed, or both
Atmospheric Stability
the resistance of the atmosphere to vertical motion. A stable atmosphere resists any upward or downward movement. An unstable atmosphere allows an upward or downward disturbance to grow into a vertical (convective current)
Cirrus Clouds
High clouds composed mainly of ice crystals - least likely to cause structural icing (since it requires water droplets)