Hail Suppression Concepts and Seeding Methods

Abstract

Most hail suppression projects have been based upon the concepts that seeding to initiate freezing in supercooled clouds will 1) reduce the supply of supercooled cloud water available for hailstone growth; and 2) produce additional hail embryos to compete for the available supercooled water. Seeding methods used to implement these concepts have included the dispersal of AgI crystals in a broadcast mode, dispersal in the updraft areas of potential hailstorms, and direct injection of seeding agents into suspected regions of hail formation. Experimental results so far seem to favor the updraft seeding and direct injection approaches, but uncertainties about actual results persist.