GEOG 214 Lecture Notes - Lecture 4: Rossby Wave, Emissivity, Horse Length
22 Feb 2016
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Exchanged between sky, surface and all surrounding objects (trees, etc. ) Absorptivity of atmospheric gases: the atmosphere is a selective absorber in the longwave, the most significant absorbing gases are water vapour (the most important), co2, O3, o2, n2o, and ch4: aerosols (particles) and liquid water in cloud if present can be dominant. Atmospheric absorption and emission: absorptivity & emissivity of atmospheric gases. Longwave radiation at the earth"s surface (a) emission. Most surfaces are opaque to longwave (i. e. , tlw ~ 0) so alw. + lw = 1. 0, and since alw = s (according to kirchhoff"s. Since s > 0. 95 it means lw is usually small (< 0. 05) Both surface emissions and surface reflections of longwaves. Longwave radiation at the surface (c) net longwave radiation flux density (absorbed) The absorbed lw at the surface is the difference between the input from above (l ) and the combined output from emission and reflected l : Longwave irradiance from atmosphere (l is given by:
