The coherent and incoherent light scattering in the vicinity of backscattering direction on the particles of cirrus clouds

The paper presents the results of numerical calculations of the scattered light intensity by large randomly oriented particles of arbitrary shapes with flat faces in the backscattering cone [170°, 180°], performed in the physical optics approximation. It is shown that light scattered in the backscattering direction for a single large particle of arbitrary shape is divided into coherent and incoherent parts, similar to a phenomenon well known in the field of multiple scattering. For models of crystalline particles of arbitrary shapes used in this work, the coherent part forms a coherent backscattering peak, whose angular dimensions are approximately equal to the ratio of wavelength/(particle size). The incoherent part is close to smooth geometrical optical solutions.