USA, cloud seeding is used to increase precipitation in areas experiencing drought, to reduce the size of hailstones that form in thunderstorms, and to reduce the amount of fog in and around airports. Cloud seeding is also occasionally used by major ski resorts to induce snowfall. Eleven western states and one Canadian province (Alberta) have ongoing weather modification operational programs . In January 2006, an $8.8 million cloud seeding project began in Wyoming to examine the effects of cloud seeding on snowfall over Wyoming's Medicine Bow, Sierra Madre, and Wind River mountain ranges.
A number of commercial companies, such as Aero Systems Incorporated , Atmospherics Incorporated , North American Weather Consultants , Weather Modification Incorporated , Weather Enhancement Technologies International , Seeding Operations and Atmospheric Research (SOAR) , offer weather modification services centered on cloud seeding. The USAF proposed its use on the battlefield in 1996, although the U.S. signed an international treaty in 1978 banning the use of weather modification for hostile purposes.
During the sixties, Irving P. Krick & Associates operated a successful cloud seeding operation in the area around Calgary, Alberta. This utilized both aircraft and ground-based generators that pumped silver iodide into the atmosphere in an attempt to reduce the threat of hail damage. Ralph Langeman, Lynn Garrison, and Stan McLeod, all ex-members of the RCAF's 403 Squadron, attending the University of Alberta, spent their summers flying hail suppression. A number of surplus Harvard aircraft were fitted with racks under each wing containing 32 railroad fuzees that were impregnated with silver iodide. These could be ignited individually or all at once, depending upon the threat. In coordination with ground units, the aircraft would lay a plume of silver iodide in front of approaching cumulo-nimbus clouds with noticeable effect. Large, active CBs were reduced to nothing. Heavy hail storms were reduced in intensity. This effective program was funded by farmer contributions and government grants.
