One hundred years later, we get the truth on cloud seeding.
In the early 1900s, after years of less-than-ideal water levels, the city of San Diego was desperate to avoid a drought. The city council caught wind of a sewing machine salesman named Charles Hatfield—who reportedly knew how to conjure rain using a chemical brew and galvanized evaporation tanks—and in 1915 they hired him. San Diego agreed to pay Hatfield $10,000 if he could fill the Morena Reservoir that winter. With his brother’s help, Hatfield built a tank and evaporated his secret mix. Colossal downpours followed, along with broken dams, marooned trains, and civilian deaths. The legend of cloud seeding was born.
Coaxing precipitation is an old venture that in the past has involved both dancing and, likely, human sacrifice. With cloud seeding, the core premise is that if you can increase the number of microparticles in rain clouds, droplets will more readily adhere to said particles, grow bigger, and fall to earth as rain and snow. After Hatfield’s mysterious experiment, it wasn’t until 1946 that Bernard Vonnegut discovered that silver iodide could theoretically be used to increase precipitation in moisture-bearing clouds.
In the ski business, Durango-based Western Weather Consultants has been cloud seeding for almost four decades for Vail and Beaver Creek. Other Colorado resorts eventually got onboard, including Telluride, Purgatory, Winter Park, Breckenridge, and Keystone; North American Weather Consultants out of Utah runs Crested Butte’s program, while Grand Junction’s Water Enhancement Authority runs Powder Horn’s. Farther west in California, Alpine Meadows has hosted the Desert Research Institute’s cloud seeding program since 1998. But that’s only a handful of the hundreds of ski areas in the U.S.
And why not more? Although Larry Hjermstad founded Western Weather Consultants based on early research, farmers, government scientists, land managers, and ski areas have been split on whether or not the dark art works. But finally, after nearly a decade of scientific sweat and more than $14 million in funding, the Wyoming Weather Modification Pilot Program has produced promising results.
For the study, designed by the National Center for Atmospheric Research (NCAR), silver-iodide generators were placed upwind of two adjacent mountain ranges in southern Wyoming—the Sierra Madre and Medicine Bow. When moisture-bearing clouds came along, one range would get the silver-iodide treatment while the other would not. This allowed for a control group of sorts. Results were measured using high-resolution snow gauges in the mountains, along with additional layers of evidence (the scientists involved liken their process to that of crime scene investigators). Sure enough, the study suggests that cloud seeding has a positive effect, increasing precipitation in moisture-bearing clouds by 5 to 15 percent. It’s not conclusive, but it does somewhat back up the anecdotal claims of a 10 to 15 percent gain.
As expected in the drought stricken West, this is big news. According to Joe Busto, the Weather Modification Program Coordinator for the Colorado Water Conservation Board, “The momentum has really been growing since the Wyoming study.” Busto hopes it’s enough to convince water districts and resorts to partner when it comes to modernizing cloud seeding equipment.
“The researchers did a fine job of having an independent, scientific, in-depth study,” says Colorado State Climatologist Nolan Doesken, who wasn’t involved in the project. “The original studies have always been challenged, never convincing anybody one way or another. This is a double-blind study with totally independent evaluators—it’s on much more solid ground.”
Cool. Excellent job, NCAR. Now make it dump. —Cody Blum
From the Early Winter 2015 issue.