Crystal CozartESC1000December 2, 2009Ch. 18 Homework2.) During absorption of radiation, the energy of a photon may initiate chemical and physical reactions in the molecules of your skin. One possible reaction is roughly analogous to cooking, and this reaction causes sunburn or tan. Alternatively, the energy of a photon may be transmitted to an electron in a molecule. In this case, the electron jumps to what scientists call an excited state. But electrons do not remain in their excited states forever. Frequently they fall back to a lower energy state, initiating emission of radiation in the process. An iron bar at room temperature emits infrared radiation and is an example of this. 3.) Albedo is the proportional reflectance of a surface. Snowfields have high albedos and reflect 80 to 90 percent of sunlight. If Earth were to cool by a small amount, snowfields and ice reflect solar radiation back into space and lead to additional cooling— which causes further expansion of the snow and ice. Most incoming radiation would reflect back into the atmosphere and the
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lower energy state, radiation warms rocks, Crystal Cozart ESC1000