GLOBAL CIRCULATION PATTERNS

A. INTRODUCTION

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

---

B. GLOBAL PRESSURE PATTERNS

• Equatorial region (0-5^o)

  • Intertropical Convergence Zone

  • thermally induced low pressure

• Subtropics (20-35^o)

• Subtropical high pressure cells

• mechanically induced high pressure

• Mid-high latitudes (40-65^o):

• Subpolar low & Polar front

• mechanically induced low pressure

• Polar regions

  • Polar high

  • thermally induced high pressure

  
  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

---

C. GLOBAL WIND PATTERNS

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

---

Polar Easterlies Subpolar jet stream in upper atmosphere longwaves   Westerlies

Horse latitudes Trade winds Doldrums

Image credit: NASA Visible Earth http://visibleearth.nasa.gov/view_rec.php?id=2431

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