From a series of 38 photographs taken during a hygroscopic flare seeding event focused on orographic cumulus over the San Joaquin River watershed in California’s southern Sierra range. (See paper in this volume.) Photos trace the dramatic change in cloud and precipitation dynamics through the hours of 1531 to 1842. Seeded cloud remains stationary while smaller cumulus clouds merge with the primary cell. This seeding event, and several other similar hygroscopic field experiments conducted by Atmospherics Incorporated over the past several years, simultaneously produced large quantities of 5-6 mm diameter graupel (snow pellets) and 3-5 mm diameter frozen droplets (hail), all reaching ground level. The latter have opaque centers surrounded by clear ice, suggesting hygroscopic seeding application may act as a catalyst for producing hailstones.
(Cover photos courtesy Tom Henderson, Atmospherics Incorporated, July 1996)