Weather Modification for Use in High Plains

The users decision process on whether or not to utilize weather modification is not the same as the decision process involved in a scientific experiment. A decision to use weather modification is based on perception of the benefits and risks by the user as well as the general scientific acceptability of the practice. Cloud seeding with silver iodide or sodium chloride is observed to induce precipitation sooner than in the natural cloud and to give increases in rainfall from clouds having less than a 30,000-ft depth. Observations of hail indicate a fewer number of large stones for seeded than for nonseeded hailstorms. Crop hail damages paid were less for seeded days than for nonseeded days. More than 2,000 radar observations of precipitation cells in South Dakota in 1972 give results consistent with the idea of cloud seeding reducing the intensity of hailstorms and inducing greater precipitation amounts from smaller clouds. Revised reporting rules are being required to insure that weather modification projects do not endanger persons, property, or the environment.