Intensity of light scattered by a large randomly oriented particle of irregular faceted shape at the backscattering cone of [170°, 180°] is calculated using the physical-optics approximation. It is shown that the backscattered light for a single large particle of irregular shape is split into the coherent and incoherent parts similarly to the phenomena well-known for multiple scattering media. For the model of irregular faceted particles assumed in the paper, the coherent part creates the coherent backscattering peak whose angular width is equal approximately to the ratio of wavelength/(particle size). The incoherent part approaches to the smoothed geometric-optics solution. For other models of faceted particles where the dihedral angle of 90° among the facets is essential, the incoherent part creates as well the incoherent backscattering peak with another angular width.

The depolarization ratio and backscattering cross sections have been calculated for shapes and size of ice crystals that are typical in cirrus clouds. The calculations are performed in the physical-optics approximation. It is shown that the depolarization ratio approaches some constant when the size of the crystals becomes much larger than the incident wavelength. For the transparent ice crystals, when absorption is absent, the magnitude of this constant strongly depends on crystal shapes. This fact allows inferring the crystal shape from magnitudes of the depolarization ratio in lidar signals. For the lidar wavelengths, where absorption of light is considerable, the depolarization ratio of lidar signals can be used for inferring crystal sizes. Such results are important for the development of algorithms interpreting the signals obtained by both ground-based and space-borne lidars.

Results of analyzing the numerical calculation of light scattering matrices for ice crystals of arbitrary shape with allowance for absorption are presented. The matrices are obtained within...

An algorithm for interpreting light backscattering matrices (LBSMs) obtained experimentally on the unique high-altitude polarization lidar of the National Research Tomsk State University in...

A new algorithm for solving the problem of light scattering by nonconvex crystals typical for cirrus clouds is presented. It is based on the beam tracing algorithm for convex particles (Institute of...

All elements of the scattering matrix have been numerically studied for particles of irregular shapes whose size is much larger than incident wavelength. The calculations are performed in the physical optics approximation for a particle size of 20 μm at a wavelength of 0.532 μm. Here the scattered intensity reveals the backscattering coherent peak. It is shown that the polarization elements of the matrix reveal the surges within the backscattering peak. The angular width of the surges does not practically depend on particle shape, but depends on the particle size. It is shown that these surges are created by interference between the conjugate scattered waves propagating in the inverse directions. The results obtained are of interest for interpretation of lidar measurements in cirrus clouds.