APPARENT SKY TEMPERATURES IN THE MICROWAVE REGION

Abstract

The problem of atmospheric radiation over narrow bands in the microwave region is considered. Equations for the radiation received at a point on the earth's surface for a particular angle of observation, and also for the integrated average over the whole sky, are presented. For convenience, the results are expressed as ?apparent sky temperatures??the comparison being a black body. The dependence of the sky temperatures on wavelength and weather conditions is brought out by a discussion of the absorption of radiation by oxygen, water vapor and condensed water droplets. Calculated sky temperature data are presented for three typical weather conditions at wavelengths of 0.30, 0.43, 0.86, 1.25, 1.80 and 3.00 cm. The causes of the wide range of temperatures encountered at these wavelengths for various sky conditions are discussed.