U.S. patent number 6315213

"A scientist from Wright Patterson Air Force Base acknowledges that planes are spraying barium salt, polymer fibers, aluminum oxide and other chemicals in the atmosphere to both modify the weather and for military communications purposes. The patent abstract specifically states: 'The polymer is dispersed into the cloud and the wind of the storm agitates the mixture causing the polymer to absorb the rain. This reaction forms a gelatinous substance which precipitate to the surface below. Thus, diminishing the cloud’s ability to rain.'"

Gah.