Arizona to fight drought by seeding clouds

Of all the potential solutions offered for Arizona's water challenges, one has a decidedly science fiction feel: planes flying over the Rockies, seeding clouds with aerosolized silver iodide to stimulate rain and snow. It's not magic or raindancing but a very real process that dates back to the 1940s. Cloud seeding works by adding ice nuclei, or the initial seed of a rain drop or snowflake, into a cloud that has extra moisture. That's typically done with silver iodide in an aerosol form. The Central Arizona Project has put about $1 million toward research since 2007, in hopes of increasing the supply in the Colorado River system.

A recent Wyoming Weather Modification pilot project suggested cloud seeding causes an increase of seasonal snow water accumulations of 5 to 15 percent and a 1.8 percent increase in stream-flows. "Percentage-wise, that might seem modest, but for the investment you put in that's actually pretty good," Mahmoud said. Compared to other alternatives for water augmentation, like desalinating seawater, cloud seeding is the cheapest option. "It's a simple way to try to have a new supply in our efforts to mitigate potential shortage on the Colorado River that could happen as early as 2016 or 2017," he said.