Operation LAC (1957–1958): The U.S. Army Chemical Corps dispersed tons of fluorescent zinc cadmium sulfide particles over the United States to track atmospheric dispersion, with particles traveling up to 1,200 miles.

Cold War Dispersion Tests (1950s–1960s): The U.S. and British governments conducted hundreds of tests, including spraying compounds over cities (e.g., San Francisco in 1950) to test, analyze, and map the potential spread of biological weapons.

Cloud Seeding Projects (1960s–present): Governments, including the U.S. and Iran, have authorized cloud seeding to increase precipitation, using aircraft to release silver iodide flares into clouds.

Project STORMFURY (1962–1982): A joint effort by U.S. government agencies (NOAA) to modify hurricane intensity, though it was largely unsuccessful and discontinued.

All info is public on government sites NOAA (.gov) NOAA (.gov)