The Scattering of Infrared Radiation from Clouds

Abstract

The scattering of infrared radiation from clouds composed of spherical water droplets has been calculated by Mie theory. For wavelengths in the range from 2.5 to 6 μ and for large angle scattering, the effective reflectivity is due to single rather than multiple scattering by water droplets. This is a consequence of the rather large absorption cross section and of the forward peak in the differential scattering cross section. The effective diffuse reflectivity under these conditions is of the order of 2% at λ = 2.7 μ and 15% at λ = 4.3 μ for scattering through angles θ ≳ 60°.