The first time I heard of cloud-seeding was in a green committee meeting discussing the water level dropping in Lake Mead. Our water table in Utah is dependent on the snow pack in the Colorado Rockies (home of the Colorado River which springs up from the Rockies). I was told that scientists have tried seeding the clouds in the Rockies to produce more snow pack resulting in water run off in the spring and summer into the Colorado River. The cloud-seeding program is a widespread effort to load passing winter storms with moisture-wicking silver iodide molecules. Still can’t fathom how this works? These seeds can be delivered by planes or sprayed from the ground into clouds.
In order to really know if it’s working, you need a controlled experiment, however, controlled experiments are impossible in this case because it is hard to know if it was really going to rain or the rain was a result of the cloud-seeding. “Successful” experiments have been conducted in Australia, France, Spain, the U.S., China and United Arab Emirates. The technique has credited the creation of 52 storms in the Abu Dhabi desert and China boasts that they used a reverse technique to prevent rain during the 2008 Olympics.
In the case of the Colorado Rocky Mountains, the cloud-seeding method uses “cold rain” which is silver iodide and dry ice (frozen carbon dioxide). There is also “warm rain” that is produced as well for lower land such as agricultural use. To read more on the specifics of “cold rain” and “warm rain” and how it’s seeded into clouds, I found this useful website but don’t want to bore you with all the details.
Is this method effective for increasing snow pack in the Colorado Rockies resulting in more water delivered to needy states like Utah, Arizona and California? According to an article in the Durango Herald, those experimenting are seeing more of a difference. An article in the Mountain Town News strongly suggests that it does. There is no doubt lots of research and experiments have been conducted in the U.S. – only time will tell as states and cities put funds towards increasing their water supply.