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GLOBAL PRESSURE AND WIND PATTERNS

A. INTRODUCTION

Major pressure zones

equatorial low, subtropical high, subpolar low, polar high

Major wind belts

Trade Winds, Westerlies, Polar Easterlies

Image credit: NASA Earth Observatory http://earthobservatory.nasa.gov/Newsroom/NewImages/images_topic.php3?topic=atmosphere&img_id=3977

B. GLOBAL PRESSURE PATTERNS

Image credit: National Weather Service Climate Prediction Center (2002) NOAA, Mean annual sea level pressure 1979-1995. http://www.cpc.ncep.noaa.gov/products/precip/realtime/clim/annual/monthly/annual.slp.html

Intertropical Convergence Zone (0-5^o)

thermally induced low pressure





Doldrums

Subtropical high pressure cells (20-35^o)

mechanically induced high pressure





Horse latitudes

Subpolar low & Polar front (40-65^o)

mechanically induced low pressure

Polar high

thermally induced high pressure

C. GLOBAL WIND PATTERNS

The Basic Pattern

Trade winds





Westerlies





Subpolar jet stream in upper atmosphere





• longwaves  





Polar Easterlies

Polar Easterlies	Westerlies	NE Trade Winds	SE Trade Winds	Westerlies	Polar Easterlies

Seasonal shifts to the basic pattern

D. LOCAL AND REGIONAL WINDS

Land and sea breezes

Sea breeze

Land breeze

Monsoon winds in Southeast Asia    

• Winter monsoon
                 



• Summer monsoon
                 

E. OCEANIC CIRCULATION PATTERNS    

East coasts: warm ocean currents





West coasts: cold ocean currents

F. SUMMARY

Four global pressure zones: high, low, high, low from poles to equator





Three global wind belts: polar easterlies, westerlies, trade winds





Pressure zones and wind belts shift north and south with the seasons





Land and sea breezes, wintern and summer monsoon





High pressure cells drive oceanic circulation: warm and cold currents