When you combine two popular objects of conspiracy theories — Area 51 and the assertion that government scientists are secretly trying to manipulate the atmosphere in an effort to develop a weather-control weapon — you get a combination that's almost as irresistible as, say, chocolate-covered bacon. The Las Vegas Tourism Bureau's official Area 51 page even tries to lure visitors to the area by mentioning that the weather control experimentation is "rumored" to take place there. .
This conspiracy theory may spring from an actual truth: According to a National Science Foundation report, the U.S. military did actually engage in Project Cirrus, a research effort in the late 1940s and early 1950s to find a way to modify clouds and use rain — or perhaps the lack of it — as a weapon. And between 1962 and 1983, the National Oceanic and Atmospheric Administration ran a project called Project STORMFURY, in which scientists tried to use cloud seeding to slow hurricane winds, though without much success [source: NOAA]. While there's no evidence that such research continued at Area 51, weather modification does sound like just the sort of trick that government scientists would try to pick up from captured aliens.