An industrial operation to produce precipitation

TitleAn industrial operation to produce precipitation
Publication TypeConference Proceedings
Year of Conference1950
AuthorsCundiff, S. A.
Conference Name18th Annual Western Snow Conference
Series TitleProceedings of the 18th Annual Western Snow Conference
Date PublishedApril 1950
PublisherWestern Snow Conference
Conference LocationBoulder City, Nevada
KeywordsWeather modification procedures

Cloud seeding (weather modification) experiments were carried out at Bishop Creek, California, during the winters of 1947-49. It was observed that clouds forming over the watershed were blown east and dispersed without precipitating. These clouds are usually deficient in nuclei and had temperatures between -10deg and -39deg C. Dry ice, distributed by airplane at the rate of 4 to 5 pounds per mile, was found to be superior to silver iodide. Precipitation occurred from 5 to 15 minutes after seeding. Over-seeding caused the dispersal of clouds. It was estimated that seeding operations increased the water yield by 14% in 1947-48 and 12% in 1948-49. The cost was approximately $200 per hour of seeding flight time, with flights ranging from 45 minutes to 1.5 hours. Approximately 50 flights were made in 1948-49.