Dispersion of Airborne-Released Silver Iodide in Winter Orographic Clouds

Abstract

Two flight plans were used for a seeding aircraft and a measurement aircraft in the study of silver iodide plume dispersion. An instantaneous line source and a continuous point source plume generation were simulated approximately by the seeding aircraft. Plume interceptions were made about an hour later by another aircraft equipped with an acoustical type ice nucleus counter. Results of the measurements are that both the vertical and horizontal diffusion of silver iodide released from airborne generators in the northern Wasatch Mountains during winter orographic storms are much lower than that desired for effective seeding. Plume-edge outward velocities are only about 0.5?1 m s?1 in the horizontal and about 0.1 m s?1 in the vertical directions, respectively.