Thermal radiation from the atmosphere

Abstract

A theoretical analysis of atmospheric thermal radiation reveals that previous formulas relating this parameter to screen-level air temperature have lacked universal applicability. New considerations indicate that the effective emittance of the atmosphere is a minimum at 273°K and that it increases symmetrically to approach unity exponentially at higher and lower temperatures. A formula is developed that meets these standards and fits experimental data from Alaska, Arizona, Australia, and the Indian Ocean with a correlation coefficient of 0.992. The atmospheric radiation R integrated over all wavelengths, is specified solely in terms of the screen-level air temperature T as R = σT4{1 - c exp [−d (273 - T)2]}, where c and d are constants having values of 0.261 and 7.77×10−4, respectively. It appears that the formula may be valid at all latitudes and seasons.