Distribution of Water in Hailstones

Abstract

A large number of photographs of thin sections of quenched hailstones have been studied to determine the most common patterns of water distribution within hailstones. The way in which water is distributed throughout the hailstone determines which of the mixing rules should be used to calculate an effective refractive index of water-ice mixture. We have concluded that the Maxwell-Garnett mixing rule for ice grains embedded in a water matrix is suitable for most graupel soaked with water. Some of the large hailstones with spongy growth suggest that a proper generalization of the Bruggeman mixing rule should be used to determine their effective index of refraction at centimeter wavelengths.