cloud seeding is a type of weather modification that aims to change the amount or type of precipitation, mitigate hail or disperse fog. the usual objective is to increase rain or snow, either for its own sake or to prevent precipitation from occurring in days afterward. cloud seeding is undertaken by dispersing substances into the air that serve as cloud condensation or ice nuclei. common agents include silver iodide, potassium iodide, and dry ice, with hygroscopic materials like table salt gaining popularity due to their ability to attract moisture. techniques vary from static seeding, which encourages ice particle formation in supercooled clouds to increase precipitation, to dynamic seeding, designed to enhance convective cloud development through the release of latent heat. methods of dispersion include aircraft and ground-based generators, with newer approaches involving drones delivering electric charges to stimulate rainfall, or infrared laser pulses aimed at inducing particle formation. despite decades of research and application, cloud seeding's effectiveness remains a subject of debate among scientists, with studies offering mixed results on its impact on precipitation enhancement. some studies suggest it is "difficult to show clearly that cloud seeding has a very large effect" in the summer of 1948, the usually humid city of alexandria, louisiana, under mayor carl b. close, seeded a cloud with dry ice at the municipal airport during a drought; quickly 0.85 inches (22 mm) of rain fell. cloud seeding since: > 1948 1948 > 1948 1948 > 1948 1948   _seeding
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