MEASURED AND MODELED SCATTERING PROPERTIES OF SIMULATED PARTICLES OF GRANULAR AND SPONGY HAIL AT MICROWAVE AND MILLIMETER-WAVE FREQUENCIES

The detailed scattering properties of single spherical particles which have been created artificially to represent particles of hail have be en measured together with the physical properties of the particles, na mely size, shape and percentage content of ice, water and air as apply ing continuously throughout the process of melting. Specifically, the types of particles represent granular hail and spongy hail. The measur ements are of extinction (total-loss) cross-section, and were taken at frequencies of 8, 10, 12, 34 and 70GHz, Models for describing the obs erved scattering behaviour are tested, and differentiation is made bet ween the results and models which apply to each of the types of partic les, the observation and implications of collapsing size of the two ty pes of particles being an important feature. For types and frequencies , the sets of results allow evaluations to be made of the ratio of the maximum cross-section exhibited during melting to the initial cross-s ection of a particle when dry.