Atmospheric Pressure And Winds Flashcards
Air pressure
Weight of atmosphere per unit area
Barometer
Instrument used to measure air pressure
Cyclone
Low pressure
Winds move counterclockwise
Weather is rainy because air is forced to rise
Anticyclone
High pressure
Winds move clockwise
Weather is clear and dry
Why does air pressure change?
1) Temperature changes
- when warm air replaces cool air; air pressure at the ground falls
- arrival of cold air higher up causes pressure at the ground to rise
2) Humidity changes
- more H2O vapor the lighter it is because H2O vapor is lighter than nitrogen and oxygen that was pushed out
Front
Boundary between any two air masses
After a cold front passes
Weather changes drastically
Temp decreases and wind speed increases
Rain ends after front passes
Stationary front
Neither air mass is displaced
Front does not move
Weather=warm front weather
Maritime tropical mT
Warm and humid
Continental tropical cT
Dry and hot
Maritime polar mP
Cold and humid
Continental polar cP
Cold and dry
Continental arctic cA
Very cold and very dry
Air mass
Huge section of air in lower troposphere with same weather throughout
ITCZ
Inter tropical Convergence Zone
Low pressure zone at equator where winds from both hemispheres converge
Air pressure is measured in ________
Millibars
Isobars connect points of _______ ____________
Equal pressure
Warm front dominant cloud
Why?
Stratus
Slope of front is gradual=stable air
Cold front dominant cloud
Why?
Cumulus
Slope is steep=unstable air
Why do fronts bring precipitation?
They force air to rise creating unstable air and clouds
4 types of cold fronts
Cold front _^_^_^_^_^_^_ Warm front _o_o_o_o_o_ Occluded front _/\_o_/\_o_/\_o_ Stationary front _/\_/\_/\_/\_/\_/\_/\_ ooooooooooooo
Occluded front weather
Same as cold front
Stationary front weather
Same as warm front
Cold front weather
Showery before with thunderstorms common
Cumulus clouds because of unstable air
After-temp decreases, wind speed increases, rain stops
Warm front weather
Thunderstorms can form but not common
Precip ahead of front
Stratus clouds form because air is stable
After-temp is warmer
Pressure
Force per unit area