New Clues for Decoding Hailstone Structure

Abstract

Within a temperature controlled cold room, using a horizontal wind tunnel and a bank of water sprayers, rime deposits of various densities were grown on rotating cylinders. Experiments were conducted at ambient temperatures of ? 25°C, ? 17°C and ° 10°C for rime densities ranging between 0. 1 and 0.8 gcm?3. After the desired thickness of rime was acquired, the cloud was intensified to produce wet growth conditions on the surface of the rime. This allowed liquid water to penetrate the porous rime structure. When the rime was completely soaked, the sprayers were shut off and the spongy deposits allowed to freeze in the airstream. Thin sections were subsequently made to allow air bubble and crystallographic analyses of the samples. Results indicate that many characteristics of natural hailstones have been duplicated.