During the Vietnam War, the U.S. Air Force laced the skies over North Vietnam and parts of Laos with small quantitites of aerosols designed to amplify the intensity of rainfall patterns by enhancing the density of clouds.

FORBES: "Cloud Computing" of the Not-So-Virtual Sort

While hundreds of studies around the world have linked climate change to phenomena including the increased frequency and intensity of hurricanes and other storms, changing rainfall patterns, drought, coastal flooding, changing disease patterns and the migration of human populations.

CNN: Environmentalists hope UN talks tough on climate change