Modeling of the spectral irradiance of elements of the earth's surface from the sky in the IR region of the spectrum

Spectral densities of the hemispherical radiance of the sky in the main spe ctral regions where thermal-imaging and thermoradiometric devices operate a re obtained on the basis of statistically sound initial data for weather co nditions typical for the middle lattitudes of Europe. These data can be use d for numerical modeling of the reflected component of the signals from ele ments and objects placed on the earth's surface, including calculation of t he spectral contrast in the absorption bands of anthropogenic gases in the "transparency windows" of the atmosphere, and also for estimating the effec tive temperatures of the background irradiances of the sky in the design an d processing of remote thermoradiometric measurements of the thermodynamic temperature of objects under conditions of the middle-latitude atmosphere. (C) 2000 The Optical Society of America. [S1070-9762(00)00510-8].