Delayed Effects of Cloud Seeding with Silver Iodide

Abstract

Apparent delayed effects of aerial cloud seeding with silver iodide are demonstrated in Smith et al.'s experiment in Tasmania. These effects reached a maximum nine days after a seeded day and were most unlikely to have arisen by chance. A possible cause of these and even more delayed effects of seeding is shown to be the enhancement of concentrations of airborne ice-nucleating bacteria by small amounts of silver iodide applied to vegetation.