SCATTERING OF LIGHT BY POLYHEDRAL ICE CRYSTALS

The single-scattering phase functions of polyhedral-shaped ice particl es are calculated by means of geometric optics and the diffraction the ory. Particle orientation is assumed to be random in space. Particle s hapes are taken both from ice-crystal classifications and from in situ measurements. The effects of particle concavity on the scattering sig nature are discussed in detail. A common feature is the pronounced for ward-scattering peak, as well as different halo peaks that are due to a minimum deviation at corresponding ice prisms. An unusual halo pheno mena, which results from a minimum deviation in a double-prism configu ration, is found and verified. The comparison of different particle ty pes shows that backscattering is a sensitive indicator for the identif ication of types of ice-crystal. Aggregate particles, like bullet rose ttes, basically show the scattering characteristics of their individua l components.