Hail Photography: An Example of the Use of High-Speed Techniques under Adverse Conditions

High-speed photographic techniques have been used to record the aerodynamics of natural hailstones falling near the ground. Two photographic systems were employed: a high-speed 16mm camera with two 1,200-W light sources and a pair of motor-driven 35mm cameras with stroboscopic illumination. Exposure time had to be on the order of 100 μs or less with Tri-X film. Both systems were powered by a portable 3-kW gasoline-powered generator. One or the other of these systems was deployed in several hailstorms during the summers of 1973 and 1974. The photographed stones were allowed to impact in a sawdust-filled box and were stored in a portable freezer for subsequent analysis. A hailpad consisting of a styrofoam square covered with aluminum foil was also set out during the photography to record size distributions and collision energies. Some preliminary results obtained for the films, the advantages and disadvantages of the two systems, and the techniques used to facilitate high-speed photography under the adverse conditions typical of severe hailstorms are examined.

Print ISSN

0361-4573

Published

1975-01

Content type

Original Research

DOI

10.5594/J13424