by Lorie Grant DeWorken

Created on: November 11, 2008   Last Updated: December 15, 2008

The 2008 Opening Ceremonies of the Beijing Olympics went off without a hitch. Beautiful venue. Beautiful performances. And a beautiful night. The Chinese put a lot of effort into every aspect of the event - including controlling the weather.

Does this mean that they provided umbrellas, ponchos and shelter in case inclement weather should break out? No. It means they went to the skies and sought to keep the inclement weather away from that night altogether. They started cloud seeding.

WHAT IS CLOUD SEEDING?

Cloud seeding can change the weather by bringing on and even changing precipitation. It can reduce fog and hail, increase the amount and intensity of rain, and result in the break up of clouds so that areas (like Olympic arenas) will be in the clear.

It may sound crazy but it's not new. It has been practiced for more than 60 years. Two scientists, Vincent Schaefer and Bernard Vonnegut, developed cloud seeding methods in 1946. The first attempt was made in November of that year using Schaefer's method. Snow fell near Mount Greylock in Massachusetts that day.

On that day, and many times since then, scientists took to the skies. They distributed chemicals in targeted upper level clouds. The idea was to simulate and accelerate the precipitation process. The chemicals - typically either dry ice or silver iodide - cause ice crystals to grow to the point that they "precipitate out" creating rain (or snow depending on the climate).

This process can be carried out from airplanes or from the ground. Reports said that the Chinese would shoot rockets or other artillery into the sky with canisters targeting the clouds around Beijing. Other scientists use devices, like generators, that will disperse the chemicals into the air currents from below.

WHO PRACTICES CLOUD SEEDING?

Countries around the world have used cloud seeding for various reasons over the years. It's a matter of general interest to many scientists who study weather and precipitation. And, of course, there those scientists like hurricane researchers who attempted to use cloud seeding to reduce the ferocity of hurricanes in the 1960s. Unfortunately, it didn't work. Perhaps they will find a way that cloud seeding research can help deter or predict other phenomena.

Many nations use cloud seeding as a way to deal with drought. Areas in the U.S., including Utah and Nevada, have been known to practice it as a way to bring moisture to their typically dry terrains. They even have state water resource divisions that manage

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