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Rainmaking: myth to reality Volume 11, issue 4, Décembre 2000

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Author
ACMG, Aérodrome Agen, 47520 Le Passage, France.
  • Page(s) : 275-80
  • Published in: 2001

Rainmaking requires unbiased scientific evidence. This paper reviews the two main weather-modifying techniques. The first method is based on Schaefer’s 1946 discovery of the ice-nucleating potential of dry ice. Silver iodide in now widely used to freeze supercooled cloud water or raindrops, thus triggering a storm or accelerating the rain process. In the 1990s, a South African team developed a new method based on hygroscopic flares capable of enhancing the coalescence process at an early cloud-formation stage. The very good results of this randomized cloud-seeding experiment prompted other programmes under way throughout the world to readopt this concept that had been abandoned in the 1960s. Rain mass was increased by more than 20%. This new strategy can also be implemented – using regular salt, sodium and calcium chloride – for hail prevention without any negative environmental impact.