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PLANETARY WIND SYSTEM. Coriolis Effect. Coriolis occurs because the Earth rotates. CORIOLIS. Earth rotates about its axis every 24 hours. Distance around the equator is 25,000 miles the earth is travelling east at 1,000 miles per hour. Distance around the Earth at 40ºN 19,000 miles
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PLANETARY WIND SYSTEM
Coriolis occurs because the Earth rotates. CORIOLIS Earth rotates about its axis every 24 hours. Distance around the equator is 25,000 miles the earth is travelling east at 1,000 miles per hour. Distance around the Earth at 40ºN 19,000 miles the earth is travelling east at 800mph. The Coriolis effect results from this difference in velocity. In the Northern hemisphere the Coriolis effect deflects movement to the right. In the Southern hemisphere Coriolis effect deflects movement to the left. The combination of atmospheric cells and Coriolis effect lead to the wind belts. Wind belts drive surface ocean circulation
Planetary Winds High Pressure Coriolis effect WIND pressure gradient force Low Pressure Winds are named by the direction they blow from.
90ºN Temperate Low LP 60ºN 30ºN Sub-tropical High - Horse Latitudes HP Equatorial Low - Doldrums LP 0º Sub-tropical High - Horse Latitudes HP 30ºS Temperate Low LP 60ºS 90ºS Wind Belts Polar easterlies South westerlies NE Trades SE Trades North westerlies Polar easterlies
convergence LP 60ºN 30ºN divergence Sub-tropical High HP convergence Inter-tropical convergence zone LP 0º 30ºS divergence Sub-tropical High HP convergence LP 60ºS 90ºS Wind Belts Polar easterlies South westerlies NE Trades SE Trades North westerlies Polar easterlies
Northern Hemisphere Polar Easterlies Blowing from the Polar High Pressure zone to about 60ºN Westerlies Blowing from Sub-Tropical High Pressure zone to about 60ºN Northeast Trade Winds Blowing from Sub-Tropical High Pressure zone to Equatorial Low Pressure zone. Southern Hemisphere Southeast Trade Winds Blowing from Sub-Tropical High Pressure zone to Equatorial Low Pressure zone. Westerlies Blowing from Sub-Tropical High Pressure zone to about 60ºS Polar Easterlies Blowing from the Polar High Pressure zone to about 60ºS Wind Belts
PRESSURE AND WIND PATTERNS SUMMARY: • There are basically three main wind belts in each hemisphere • Trade Winds • Westerlies • Easterlies • Trade winds lie between 30degrees N and S of the Equator • Caused by movement from High-pressure at the tropics towards low pressure at the equator • They are deflected by the Coriolis Effect • TO THE RIGHT IN THE NORTHERN HEMISPHERE • TO THE LEFT IN THE SOUTHERN HEMISPHERE • Westerlies flow polewards from the high-pressure tropical areas towards the mid-latitudes • Again they are deflected • Easterlies - Small belts of wind flow out from the poles from the east then to the west in both hemispheres • Only in winter in the Northern hemisphere
OCEAN CURRENTS
OCEAN CURRENTS • PATTERN OF OCEAN CURRENTS • EXPLANATION OF OCEAN CURRENTS DVD – Power Of the Planet (Oceans)