AS101 Lecture Notes - Lecture 11: Greenhouse Effect, Exoplanet, Hydrosphere
Document Summary
Earth"s atmosphere is unique quite different from that of venus, mercury, mars and our moon. First, for the record, earth"s atmosphere is about 77% n2, 21% 0 , 1% argon, with smaller 2 amounts of h o, co , and other gases. The pressure at ground level is 1 bar or about 101 2 2 kpa . The atmosphere was formed mainly from outgassing through volcanic activity, of which waterandco arethemainconstituents. thisisthesameasonotherterrestrialplanets. Or, putting it slightly differently, but more completely: whydidearthretainitswater,inoceans,rivers,andtheatmosphere,andvenusand. Before we answer these questions let"s review the structure of earth"s atmosphere. The diagram below shows the changes of temperature and pressure with height from the surface. Notice the relative location of clouds (below which various weather patterns form), the location of the important ozone layer, and the wildly-varying temperature with changes in vertical height or altitude. The blue line indicates the temperature variation; the pressure variation is linear with altitude.
