“The Council of the American Meteorological Society recently summed up the present evidence for the effectiveness of cloud-seeding. Its verdict: Not proven. Conditions favorable for artificial rainmaking, the statement points out, are very much the same as those which usually lead to natural rain. Says the Council: ‘Cloud-seeding acts only to trigger the release of precipitation from existing clouds.’ There appears to be no convincing evidence that ground-based silver iodide generators can increase rainfall in flat country. They seem effective only in cold weather and in regions where a mountain range forces the air to rise. The seeding of inactive cloud formations may act to dissipate them rather than cause them to produce rain.”
—Scientific American, July 1957
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