• Preliminary / Review Questions
  
  
• Idealized Belts - in a perfect world
  
  
• Intertropical Convergence Zone (ITCZ)
  • surplus of insolation
    • thermally induced "trough"
    • shifts with sun's movement
  • globe-circling zone of low pressure & clouds
    • rising and unstable air
    • area known as "Doldrums" (very calm)
  • large-scale updrafts pump enormous amount of energy into atmosphere
    • sensible heat and latent heat of condensation
      
      
• Subtropical High (STH)
  • centered at approx. 30 degrees north and south latitude
  • derived from ITC energy and upper atmospheric subsidence
    • dynamically induced "ridge"
    • shifts with sun’s movement
  • creates world's major deserts
  • at sea - associated with "horse" latitudes
    • (Note: not nearly as calm as "doldrums")
      
      
  • source of two (2 of 3) major global wind systems - Trade Winds and Westerlies
  • Class Exercise

Pacific High Azores High (off Africa)

• Trade Winds (Commerce Winds)

• most consistent winds blowing from east
• originate as warm, dry winds
• winds then evaporate large amounts of water contained in water vapor
• releases moisture when encountering landmasses (like Hawaii)
  
  
• Westerlies (winds of the mid-latitudes)
  • winds blow from west (geostrophic winds)
    • not as consistent as Trade winds due to landform barriers
    • brings in much winter storms
  • Rossby wave - meandering flow or undulation in jet stream
    • mixing of northerly cold air and southly warm air
    • sometimes resulting in severe weather
      
      
• Polar Highs - Polar areas and interior landmasses
  • cold sinking air - thermally induced
  • Siberian High and Canadian High
    
    
• Polar Easterlies
  • third (3rd) broad scale global wind system
  • most of the area between the polar highs and 60 degrees latitude
    
    
• Subpolar Lows
  • 60 degrees latitude - dynamically induced
  • collision of air masses (cold poleward & warmer adjacent)
  • resulting in rising air or low
    • So. Hemisphere - continuous belt due to ocean
    • No. Hemisphere - cyclonic cells (Icelandic Low and Aleutian Low)

Monsoons- seasonal reversal of winds

Example: South Asian Monsoons inland during summer outward during winter