SCATTERING OF SOLAR ENERGY BY CLOUDS OF “LARGE DROPS”

Abstract

For the case when absorption is negligible, the direct and scattered solar beams have been followed down into clouds of ?large? spherical waterdrops, to calculate the distribution of the generation of diffuse energy in the cloud. The generated diffuse energy is considered to obey a simple diffusion equation, from which the cloud albedo has been computed as a function of the cloud thickness, the mean free path, and the sun's zenith distance. One of the main results is the marked variation of albedo with zenith distance, especially for ?thin? clouds. The results are compared with observations, and it appears that the dissipation of stratus clouds is often accompanied by a reduction in the effective scattering radius of the cloud drops.