Resource materials on Global Warming & the Greenhouse effect  & Energy Pollution
                        EPA Global Warming site  
                        Earth Portal - Nat'l Council Science & Environment
                        CNN Global Warming site  
                        Global Warming Information page 
                        Woods Hole Oceanographic Institute page
                       
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Greenhouse Effect 
    Solar radiation warms the surface of the earth in several ways. A portion of the sun's rays are reflected back into space by the earth's atmosphere. Some rays are dispersed and scattered by the molecules in the atmosphere. Some rays penetrate the earth's atmosphere and reach the surface of the earth. 
    The radiation reaching the earth's surface is largely absorbed resulting in surface warming. Much of this absorbed energy is eventually re-radiated in longer infrared wavelengths. As it leaves this energy interacts with the atmosphere and is reflected back to the earth's surface by atmospheric molecules. This reflected energy further warms the surface of the earth.
    The molecules responsible for this phenomenon are called greenhouse gases, i.e. water (H₂O), nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂) because they act like the glass in a greenhouse, trapping re-radiated energy. Without these gases most life on earth would not be possible, as the surface temperature of the earth would likely be about 60°F colder.
    Greenhouse gases act like an insulator or blanket, keeping the heat in. Increasing the concentration of these gases in the atmosphere increases the atmosphere's ability retain heat. Therefore too great a concentration of greenhouse gases can have dramatic effects on climate and significant repercussions upon the earth.