Wyoming cloud seeding experiment modestly increases snowfall

Nature : In the western US, winter snowpack, an important water resource for many communities, has been study to evaluate the effectiveness of cloud seeding for increasing snowfall in the Medicine Bow and Sierra Madre Ranges. The two mountain ranges are situated relatively close to each other and experience similar weather conditions. When supercooled water was detected in clouds approaching the mountains, the clouds over one range were sprayed with silver iodide particles, and those over the other, which served as the control, were not. The 118 instances of cloud seeding that resulted were not deemed enough by the researchers to form any firm conclusions. However, by eliminating parts of the test that went wrong, the researchers found that seeding resulted in 5–15% more precipitation. As a result, they recommended the state start a cloud-seeding program.