Ecology: Chapter 2
The Physical Environment: Climate

Composition & Structure of the Atmosphere

  • The Earth's atmosphere is held in place by gravity.
  • The atmosphere is densest at the surface and rapidly thins upward.
  • 97% of the atmosphere is found within 18 miles of the Earth's surface.
  • Gasses that make up the atmosphere
  • Changes in atmospheric CO2
  • Atmospheric pressure
  • Vertical Distribution of Atmospheric Pressure
    • 50% of the Earth's atmosphere found below 20,000 feet.
    • 95% below 65,000 feet


Earth - Sun Relationships


Mechanisms of Heat Transfer

Heat Budget




monthly mean temperature

how mean monthly temperatures are calculated

annual mean temperature

annual temperature range (northern/southern hemisphere land distribution)

  • isotherms
  • maximum temperature records
  • minimum temperature records

temperature controls

Moisture & Atmospheric Stability

  • hydrologic cycle
    • precipitation
    • evaporation/transpiration
    • infiltration
    • runoff
  • water phases (states)
    • solid
    • liquid
    • gas
  • latent/sensible heat
    • latent heat of vaporization
    • latent heat of fusion
  • evaporation/condensation
  • sublimation/deposition
  • phase changes
  • phase change calculations (.pdf file)
  • water vapor content of air - absolute humidity and mixing ratio are similar. Both are expressed as the quantity of water vapor contained in a specific amount of air.


Under standard conditions (25oC, 1 atm), the density of air is 1.168 kg/m3. Therefore,
1kg of air would have a volume of 0.8562m3. To summarize..... 1kg of air has a volume about 15% smaller than 1m3.


                                     mass of water vapor (grams)

  • absolute humidity = ---------------------------------
  •                                 volume of air (cubic meters)


  •                                 mass of water vapor (grams)
  • mixing ratio          = ---------------------------------
  •                                 mass of dry air (kilograms)



DALR =   - 1.0oC/100m
WALR =  +0.5oC/100m
                 - 0.5oC/100m