Wind
Air
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Made of gases—fluid!! (it flows)
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Movement of air caused by differences in air pressure (uneven heating= convection currents (page 126))
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Air moves horizontal; from high pressure to low pressure
Measuring Wind- Described by speed and direction
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Direction Tool: Wind Vane (Wind swings vane so one end faces the wind)
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Name of wind tells you where the winds comes from (South winds come from the sound and head north)
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Speed Tool: anemometer
Wind Chill Factor
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Removes body heat
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Stronger wind= more cooling
Local Winds- blow over short distances
Be able to use chart
to find wind chill
Caused by unequal heating of Earth’s surface in a small area
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It takes more energy to heat a body of water that it does to heat up the equal amount of land
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Land cools more quickly than water
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Sea Breeze – during the day
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Air over land becomes warmer than air over water
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Warmer air expands and rises ( leaves a low pressure area)
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Cool air blow in from the sea to fill low pressure area
Land Breeze- only at night
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Air over land becomes cooler than the air over the water
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Warmer air over the water expands and rises
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Cool air from land moves in under it
Global winds
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Land cools more quickly than water
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Air over land becomes cooler than the air over the water
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Warmer air over the water expands and rises
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Cool air from land moves in under it
The angle of the earth changes the way the suns energy spreads out.
Sun’s energy is spread = less heating of the surface
Temps at the poles are lower because they get less light energy
Global Convection Currents
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Develop global winds
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Giant convection currents in the atmosphere
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Warm air rises at the equator and cool air sinks at the poles
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Causes wind to blow from the poles toward the equator
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Higher in the atmosphere, air flows away from the equator toward the poles
The Coriolis Effect
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If earth didn’t rotate global winds would blow in a straight line
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Earth rotates from west to east
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Rotation makes winds curve- CORIOLIS EFFECT
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Winds blow and earth rotates underneath
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Northern Hemisphere: winds gradually turn right
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Southern Hemisphere: winds curve to the left
Doldrums
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Near the equator (large amount of sun’s energy)
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Warm air constantly rising- creates area of low pressure
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Cool air moves into the area but is warmed quickly
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Rises before it can move very far
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Little horizontal motion= weak winds
Horse latitudes
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Warm air from equator rises and divides heading
north and south
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Air stops moving toward the poles and sinks
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Very calm “falling” air
Trade Winds
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Cold air over horse latitudes sinks and creates an area of high pressure
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High pressure causes wind to flow towards and away from the equator
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Wind towards the equator are turned west
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Northern hemisphere- winds blow from northeast
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Winds away from the equator are turned east
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Southern hemisphere- winds blow from southeast
Prevailing Westerlies
Called westerlies because they blow from west to east
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Between 30˚ and 60˚ north and south
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Turned eastward by Coriolis effect
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Blow away from Horse Latitudes
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Northern Hemisphere: from southwest
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Southern Hemisphere: from northwest
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Important to weather of USA
Polar Easterlies
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Air near the poles is cold
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Sinks and flows toward lower latitudes
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Coriolis effect shifts them to the west
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Meet prevailing westerlies at 60˚ north and south
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Creates a polar front
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Mix of cold &warm air effects weather in the USA
Jet streams
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10km above earths surface
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Band of high-speed winds
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100s of km wide
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Blow from west to east
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Have a wavy path
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200-400 km/hr