<title>Absorption and scattering of optical radiation by a crystal cloud</title>

Abstract

Using the experimental data available on the microstructure of crystal clouds, a new model of the ice cloud microstructure is proposed. The model we propose allows for shapes, size, concentration, and orientation of the ice crystals. Using this microstructure model, we have calculated the phase scattering function, absorption efficiency, and the single scattering albedo of crystal clouds in the visible and infrared spectral regions. Calculations of the optical properties of an individual ice crystal are being done using the geometric optics approach with the account for the diffraction effects on the crystals having the size larger than the wavelength of incident radiation. The view of scattering phase function is shown to be mainly dependent upon different cloud microstructure parameters, provided that crystals of some shape dominate in the ensemble. The absorption efficiency and single scattering albedo of an ice cloud for the optical radiation are, to a high degree of accuracy, determined by the ratio of the ice content to the extinction coefficient of the cloud.