Not far from the Dead Dog Saloon, behind a body shop on the main street of Grantsville, Utah, stands a rusting, four-foot-tall metal box. The box sits atop a tank of gaseous silver iodide that, when fired up, sends a plume downwind toward the nearby Oquirrh Mountains. Once carried up on the wind, each silver iodide crystal forms a core, or nucleus, around which water droplets collect. Since silver iodide has a crystalline structure similar to that of ice, it allows the tiny water droplets to coalesce until they are big and heavy enough to fall out of the sky, ultimately increasing snowfall between 10 and 15 percent a year. That’s more water for later release across the state’s thirsty desert during spring and baking summer, more water for irrigation, livestock, human consumption, and sports. It means millions of dollars in water-related revenues for the state’s economy every year.
The Utah cloud-seeding effort comes courtesy of North American Weather Consultants, America’s oldest weather modification company, located in an upscale office park in nearby Sandy, Utah. Founded in the 1950s, the group is currently run by two solid-citizen scientists with commercial aims, Don Griffith and Mark Solak, who have spent their careers working in privately funded weather modification efforts around the country and the world.
In Colorado they seeded the Gunnison River drainage, a series of reservoirs and dams in the west of the state. In California they run seeding programs for the Santa Barbara County Water Agency, a group that says the effort may increase rain in target areas up to 20 percent a year.
In reality, cloud seeding is pretty low tech: A tank of silver iodide is topped by a burner and surrounded by a perforated-metal wind arrester. The whole contraption is hooked to a tank of propane to provide the flame and warmth that lifts the silver iodide into the atmosphere. ”We’ve got lots of cloud-seeding units in mountainous areas all around Utah,” Solak says. When wind, temperature, and humidity are just right, the company calls local residents, who are paid a fee to go out and turn on a cloud-seeding unit, sending a plume of silver iodide downwind. Why an array of cloud seeders? Although a single plume cannot change the world, a group of such seeders, each responsible for a small shift in precipitation, can often tilt the balance locally, driving rainfall or decreasing the intensity of storms.
“In weather modification, the uninitiated think you must make huge impacts on the atmosphere to get a desired result,” Griffith says. “But it’s actually the opposite. If we just make tiny modifications to existing conditions, little touches here and there, the changes then cascade upward using the existing weather’s natural actions, and that’s what gets the biggest results.”
