Seeding clouds to produce precipitation

Dr. Vincent Schaefer undertook the first weather modification experiments for General Electric in 1946. Cloud seeding companies use aircraft or ground generators to release silver iodide particles into clouds when temperature and moisture are ripe for rain. Attracting clumps of moisture, the silver iodide particles trigger formation of ice crystals which then fall as additional rain or snow.

Cloud seeding requires that cloud contain enough moisture for the silver iodide crystals to tip near-saturation into rain or snow.

Estimates of increases in precipitation resulting from weather modification programmes range from 10 to 15 percent over normal rainfall in the wintertime northern hemisphere areas to as much as 25 percent in tropical regions.