Global Wind Paerns. specific. higher. convection. rises. rotates. equator Equatorial. Subtropical High. long. lower. troposphere. sinks.

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1 Global Wind Paerns Global Winds Winds that b steadily from direcons long over distances. specific Created by the of Earth s surface. Result of Sun striking the surface at angles near the equator and at much angles near the poles. unequal er er heating convection Giant currents in the rises Warm air at equator and cold air at the poles troposphere sinks Creates pressure at equator and pressure at poles Surface winds b from to pressure areas Global winds would simply f directly from the poles to the equator creang one large convecon cell in each hemisphere: However, the Earth is not, it rotation stationary Earth s is responsible for breaking the rotates wind belts convecon cells into smaller versions known as Smaller convecon cells: Hadley cell: equator 30 0 Air rising at the and sinking at latude Equatorial Low Rising air known as the Subtropical High Sinking air known as the 1

2 60 0 N 30 0 N S Smaller convecon cells: Ferrel cell: Air sinking at latude and rising at latude Subtropical Sinking air known as the Subpolar High Low Rising air known as the 60 0 S 60 0 N 30 0 N S Smaller convecon cells: cell: Air rising at latude and sinking at latude Subpolar Rising air known as the Low High Sinking air known as the 60 0 S 60 0 N 30 0 N The Earth s rotaon also causes the winds within each belt to curve through a process called the Coriolis Effect S 30 0 S 2

3 Coriolis Effect Earth rotates from the to the (This includes objects on or near its surface) Earth s surface has different rates of at different latitudes faster West at the equator ser at the poles rotation East Coriolis Effect Obeying Newton s first law of moon (the Law of Intera) : An air mass aempts to maintain the speed of its point of origin away If moving from the equator, it will eventually be faster moving than the land surface be it. toward If moving the equator, it will eventually be ser moving than the land surface be it. Coriolis Effect The direcon of the curve can be simplified as fols: right Winds curve to the (from their point of origin Northern ) in the Hemisphere left point Winds curve to the (from their H L L H s >>> 60 0 N 30 0 N FAST >>>>>>> 0 0 of origin Southern ) in the Hemisphere H 30 0 S L H 60 0 S Trades Trade Winds ( ) Hadley Within the cell between the latudes of Equatoral Low and (or between the Subtropical High and the ) 3

4 Trade Winds The Coriolis effect causes the winds in the Northern Hemisphere right to turn toward the and the winds in the Southern Hemisphere to turn toward the. left Trade Winds point of origin All winds are named aer their. Results in winds called the in the Northern Hemisphere and the in the Southern Hemisphere Trade Winds All winds are named aer their. Results in winds called the in the Northern Hemisphere and the Trades in the Southern Hemisphere point of origin Northeast Southeast Trades NE Trades SE Trades Prevailing Westerlies ( ) Ferrel Westerlies Within the cell between the latudes of Subtropical High and (or between the Subpolar Low and the ) influence Major in our weather paerns 4

5 Prevailing Westerlies The Coriolis effect causes the winds in the Northern Hemisphere right to turn toward the and the winds in the Southern Hemisphere to turn toward the. left Prevailing Westerlies Results in winds coming from the in the Northern Hemisphere and from the in the Southern Hemisphere Prevailing Westerlies Results in winds coming from the in the Northern Hemisphere and from the in the Southern Hemisphere Southwest Northwest Westerlies Easterlies ( ) Easterlies Within the cell between the latudes of Subpolar Low and (or between the High and the ) Westerlies 5

6 Easterlies The Coriolis effect causes the winds in the Northern Hemisphere right to turn toward the and the winds in the Southern Hemisphere to turn toward the. left Easterlies Results in winds coming from the in the Northern Hemisphere and from the in the Southern Hemisphere Easterlies Results in winds coming from the in the Northern Hemisphere and from the in the Southern Hemisphere NE SE Easterlies Summary Slide Easterlies 6

7 Planetary Wind and MOISTURE BELTS in the Troposphere Doldrums Near the equator Warm air rises steadily Cool air moves into the area, but it is quickly warmed and rises before it moves along the surface very far Very lile horizontal moon = lile to no winds Near the subtropical Horse Latudes Cool air sinks very vercally resulng in a small region with very lile horizontal movement of air Hundreds of years ago, sailors stranded in these areas ran out of food and water for their horses and had to throw them overboard Two in each hemisphere: Jet Streams Subtropical Jet 1. Front Jet 2. Very altude winds (somemes as as 10 km above Earth) West East B from to North South wavy Meander and along a path Hundreds of km wide; only a few km thick (speeds of km/h) ~200 MPH 7

8 One more quick thing concerning winds. Local Winds Sea Breezes: faster In the daytime, land heats than water. Warm rises air and creates a pressure area over the. sinks Air over the relatively water creating a pressure area land cool Wind will b from to. origin Breeze named for point of. Sea Breezes: Local Winds Land Breezes: Local Winds Hand draw a daytime picture here. In the nighttime, land cools than water. air and creates a pressure area over the. faster Cool sinks rises land warm Air over the relatively water creating a pressure area Wind will b from to. origin Breeze named for point of. Local Winds Land Breezes: Hand draw a nighttime picture here. Jan 31 8:08 AM 8