Global WindsGlobal WindsChapter17Chapter17

Formation of WindFormation of Wind

warmer air = less dense = rising air warmer air = less dense = rising air

(lower pressure)(lower pressure) colder air = more dense = sinking air colder air = more dense = sinking air

(high pressure)(high pressure)

Global Wind

Where in the world would there be HIGH pressure?

poles

Where in the world would there be LOW pressure?

equator

HADLEY cells

Hot air rises; cold air sinks Vertical motion that causes global

wind

What direction to winds flow?

Wind flows from HIGH to LOW

Coriolis EffectCoriolis EffectEarth’s rotation causes wind to:Earth’s rotation causes wind to:curve to the right in the N. curve to the right in the N. Hemisphere ; left in the S. Hemisphere ; left in the S. HemisphereHemisphere

What is global wind?What is global wind?

-General -General movement of air movement of air worldwide due to pressure worldwide due to pressure differences at the equator and at differences at the equator and at the polesthe poles

-caused by temperature difference-caused by temperature difference

Three global wind beltsThree global wind belts

Trade windsTrade winds (0- (0-30˚)30˚)

blow from NEblow from NE Prevailing Prevailing

westerlieswesterlies (30-60˚) (30-60˚)• Blow from SWBlow from SW

Polar easterliesPolar easterlies (60-90 ˚)(60-90 ˚)• Blow from NEBlow from NE

RealityReality

Places without windPlaces without wind

Doldrums (equatorial low) Doldrums (equatorial low) - zone - zone near the equator O ˚near the equator O ˚

Horse latitudes (subtropical Horse latitudes (subtropical high)-high)-(30˚)(30˚)

Jet StreamJet Stream Bands of wind in upper troposphere/lower Bands of wind in upper troposphere/lower

stratospherestratosphere Blows from west to eastBlows from west to east North of JS= coldNorth of JS= cold Moves Pressure systems Moves Pressure systems

What causes wind?