Experimental and theoretical modelling of scattering properties of melting ice spheres at microwave frequencies

The authors present newly obtained experimental and theoretical results for the scattering behaviour of melting ice spheres and, in particular, relates to the situation where concentric layers of water and partially melted ice and hard ice are present. Hard ice particles supporting a thin surface layer of water exhibit an increase in scattering relative to dry ice particles of the same radius. These particles are most likely to occur in strongly convective atmospheres as hailstone or graupel structures and can still contribute to the radar `bright band´ effect when the feature is not broken-up by convective cells. It is often possible to observe bright bands in the aftermath of heavy hailstorms. Typical measured results which illustrate the enhancement are plotted together with theoretical results (based on Mie theory) for spheres wholly composed of water and ice