Extinction and Liquid Water Content of Fogs and Clouds

Abstract

The normalized extinction cross section (efficiency for extinction) Q_ext is approximated by a linear function of the size parameter x, and a linear relationship (independent of the size distribution) between the volume extinction coefficient of a spherical polydispersion of water droplets and the liquid water content is derived. The wavelength at which this linear relationship is valid is determined by the radius of the largest droplets present in considered distributions. For the case of nonprecipitating clouds and fogs the suitable wavelength is A λ=11µm.