Cloud seeding showered in controversy
We all need water to survive. Getting just the right amount, however, can be tricky. In nature, it often seems like we are dealing with extremes. While one part of the country deals with raging floods, another area is parched with drought. For the areas that aren’t getting enough water, scientists have long tried to figure out ways to “help” mother nature along or modify the weather in some way to get more rain out of passing clouds.
In 1946, Vincent Schaefer, carried out one of the first scientific experiments in weather modification. He was a chemist and meteorologist working for the General Electric Co. laboratory in Schenectady, N.Y. On Nov. 13, he flew an airplane up to a layer of clouds near Albany and sprinkled into them three pounds of dry ice (which is just solid carbon dioxide). In five minutes, snowflakes were falling from those clouds.
Cloud seeding works by adding additional condensation nuclei to clouds. In the cold rain process, which occurs in latitudes outside of tropical areas, water vapor (the gaseous form of water) needs a particle to condense on to form the small water droplets and ice crystals that make up our clouds. Naturally occurring nuclei include salt, air pollutants, clay dust, vegetation debris, even bacteria. Experiments have shown that man can “encourage” clouds to grow, possibly increasing their rainfall, by adding additional condensation nuclei to the cloud. This can be accomplished by aircraft (or other means), which can “seed” clouds with either dry ice or silver iodide.
Cloud seeding has become big business. Atmospherics Inc., a company out of California, makes millions of dollars providing weather modification services which also can include fog dispersal and hail suppression. This year, seven states in the drought plagued west including California, Arizona, Wyoming, Utah, Nevada, Colorado and New Mexico are considering a joint cloud seeding project that would hopefully increase snow pack over the mountain ranges in Utah and increase precipitation along the Colorado River’s watershed. A cloud seeding analysis showed that more than 1.1 million acre-feet of new water on average could be generated each year, which is about 10 percent of the average 15 million acre-feet carried annually by the Colorado River. On its own, Wyoming is currently involved in a 5 year $8.8 million dollar project with a company called Weather Modification Inc. to seed clouds in the hope of increasing snowfall in the Medicine Bow, Sierra Madre and Wind River mountain ranges. The value of the additional run-off could be worth up to $4.9 million dollars each year, not including the values for generating more hydroelectric power, enhancing recreation and tourism, improving water quality and other environmental benefits.
Not all scientists are convinced, however, that cloud seeding is always effective. In experiments with the atmosphere, it is never possible to have a true “ontrol”group. Even in cases where it does seem to work, there is the issue of cost-effectiveness. Finally, there is an issue of ethics. By seeding clouds in one location to produce more rain, does one effectively “steal” rain from areas downwind? In China, where 3,000 plus people are employed in the “rain-making” field, neighboring cities have made just that claim.
Back in the United States it remains to be seen whether cloud-seeding will have any substantial impact on relieving the long-term drought in the western states. With the potential for La Niña conditions to develop in the next couple of months, areas already dealing with drought will see little relief if not worsening circumstances. The potential for much needed moisture in the southeast and gulf states, on a large scale, may ride on the Atlantic hurricane season, which officially began on June 1 and runs through Nov. 30.