Download 3 Air pressure

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Force that is exerted by air,
it presses down on Earth’s
surface
•Measured with a Barometer
• Higher elevation =
less pressure
• Bc molecules are
farther apart…..
Because of denisty
Highs are regions of cold,
heavy air (high air pressure)
Lows are regions of warm,
light air (low air pressure)
•“Highs”
•Center of air masses
•Clear skies, dry weather,
gentle winds
•Air currents will move out
•Winds blow clockwise in northern
hemisphere
•“Lows”
•Edges of air masses
•Cloudy, wet, strong, gusty
wind
•Air currents will move in
•Winds blow counterclockwise in
northern hemisphere
When air moves from HIGH
pressure to LOW pressure,
winds are created
•Horizontal movement of
air
•Cool, dense air moves
toward warm, less dense
air
•Direction from which air is
COMING FROM
•Wind vane = points in the
direction wind is coming
from
Wind •How fast air is moving
Speed •Wind speed increases when
difference in air pressure is
high
•Up & Down movements of
Air
air
Current
WARM
COOL
Global •Large system of winds around
Earth
Winds
•Caused by changes in air
pressure
Equator = warm air rises & moves
toward poles (low)
Poles = cool air sinks & moves toward
equator (high)
•Curve as they move from high 
low regions bc of Earths rotation
Coriolis •Due to Earth’s Rotation
•Northern
Hem
=
winds
&
Effect
ocean currents curve RIGHT
•Southern Hem = winds & ocean
currents curve to LEFT
In the Northern Hemisphere what a
sight.
A moving object drifts to the right.
If all this seems a bit too much to
rehearse,
Remember, the Southern
Hemisphere does it all in reverse.
Prevailing •Blow in same direction at a
latitude
Winds
•Westerlies = blow from
the west in the middle
latitude
•Trade winds = blow from the
east, in the tropics.
Jet
Streams
•Global winds
•Belts of high speed air in
upper atmosphere
•West  East
Sea
breeze
•Breeze from sea 
land
•Cooler & heavier
•Pushes warmer & lighter air
above land UP
•Breeze from land  sea
Land
•At
night,
land
cools
faster
breeze
than water  air becomes
cooler & heavier
•Moves to water & pushes
warmer, lighter air UP