Ch 6 Basic Weather Theory Flashcards
4 atmospheric levels
- Troposhere (36,000’)
- stratosphere (160,000’)
- mesosphere
- thermosphere
Composition of the atmosphere
78% nitrogen
21% oxygen
1% other gases
Atmospheric circulation
The movement of air relative to the earth’s surface
Convection
the circulation of cold air sinking and replacing warmer, rising air.
Three-cell circulation pattern
_Polar Cell (60º - poles) _Ferrel Cell (30º-60º latitude) _Hadley Cell (equator - 30º)
Isobars
measured in millibars - plotted pressure readings on weather map. Usually drawn with 4 millibar distance
Pressure gradient
change in pressure over distance
Ridge
an elongated area of high pressure (surrounded by low)
Trough
Elongated area of low pressure
Col
neutral area between two high or low gradients, or the intersection of a ridge and trough
Pressure gradient force
The general movement of cool, dense air of highs into the warm, less dense air of lows.
Coriolis ofrce
The movement of the earth causing a deviation in path of a moving object
Frictional force
about 2,000’ agl, friction caused by the earth’s surface slows the moving air reducing the coriolis force
Sea breeze
During the day cool air coming in from the water over the warmer land air
Land breeze
At night, cool air from the land blows over the warmer air at sea
