Aug 272002
Authors: Helyna Bledsoe

Cloud seeding, an experimental technique to increase rain or snowfall, may not be able to save Colorado from another summer of fires and water restrictions, according to one CSU professor.

“The increase could be between five to 10 percent,” said William Cotton, a professor of atmospheric science. “[Cloud seeding] may increase precipitation but it is very modest. It’s not going to be a drought breaker.”

The Weather Modification Association published an informational pamphlet that explains the cloud seeding process.

As the temperature rises, vapor molecules in the air can increase their volume. When that air is cooled, excessive water that has condensed in the vapor molecules begins to form cloud droplets. Cloud droplets form around microscopic aerosol particles in the atmosphere. Clouds consist of many tiny cloud droplets, and it takes about one million droplets just to produce one raindrop.

The summer is coming to a close and the most essential part of the year for precipitation is rapidly approaching.

When cloud droplets reach the mountains, the moist air is lifted and swiftly cooled. These super-cooled particles usually retain roughly 90 percent of their precipitation. To seed these clouds, ice-forming substances are added. Silver iodide is the most common component added to clouds by airplanes or ground devices. Not all seeding projects are a success, but studies have shown that some projects have increased precipitation by up to 15 percent.

Over the past year, the amount of water in Colorado has reached an extremely low level due to little precipitation. This problem has left some scientists looking for ways to get more snow this winter.

Colorado’s oldest industry, agriculture, is faced with extinction. According to the Ag Journal, a publication geared at farmers and ranchers, 50 percent of the cattle herds that have been an essential part of Colorado for over a century have been sold because there hasn’t been enough water to sustain them. Also, 50 percent of the winter-wheat crop has been lost, meaning feeding cattle this winter will be an enormous challenge.

Cloud seeding, a process used for decades by ski resorts, is providing hope for some. According to the World Meteorological Organization, cloud seeding projects are currently being implemented in more than 40 countries. The Denver Water Board is considering generators to seed clouds over the mountains in hopes of increasing water levels.

“If the results would help drought ridden areas, the experiments would be worth the effort,” said Audrey Padgett, freshman equine science major.

Cotton also mentioned the fact that cloud seeding is easier to do in the winter than in the summer months because “winter storms are more predictable and consistent.”

Dr. Cotton feels that the benefit versus the cost should be weighed when determining the productivity of cloud seeding.

“Cloud seeding is like the pimple on the butt of nature,” Cotton said.

Cotton thinks it is appropriate to find the normal water yield and then compare it to the possible increase in precipitation and cost of seeding.

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