The Glaciation of an AgI-Seeded Cumulus Cloud

Abstract

Records from an airborne continuous cloud particle collector showed distinct differences in particle characteristics between an unseeded and a seeded cumulus cloud. The unseeded cloud consisted primarily of supercooled water droplets and the seeded cloud entirely of ice particles at the observed levels. Complete glaciation was achieved by AgI seeding even at the relatively warm temperature of ?7C. The AgI acted as efficient ice nuclei even though introduced through a warm cloud base with temperatures above 0C. The observed concentration of crystals was considerably larger than would have been predicted from the standard AgI generator calibration data. Large crystals were observed clustered together in the fully glaciated seeded cloud.