On November 13, 1946, snow caused by chemicals “seeded” in clouds over upstate New York fell near Mount Greylock, Massachusetts. Dry ice was dumped into the clouds from an aircraft.
Since then, governments around the world have used cloud seeding for both military and civilian purposes. From 1967 until 1972, the United States military conducted Operation Popeye, which seeded clouds in Vietnam with silver iodide. This had the effect of extending the monsoon season by a month, making supply trails in North Vietnam muddy and difficult to travel. After the Chernobyl nuclear disaster, Soviet military pilots seeded clouds to cause rain over Belarus, which would remove radioactive particles from clouds heading toward Moscow. Austria uses cloud seeding to prevent hail formation during rainstorms. In China and Australia, cloud seeding is used to increase rainfall in areas experiencing drought.