The transfer of long-wave radiation in a model of broken clouds constructed on the basis of Poisson point flux is investigated. Formulas are obtained for the expected value of the radiance, taking into account the influence of finite horizontal dimensions of clouds on the radiation field. The results of calculations show a difference of 2--8¿K between the mean brightness temperatures of stratus and cumulus clouds in the wide range of variations of optical-geometric parameters and viewing angle. ¿American Geophysical Union 1987