Product More than 100 seeding generators from Winter Park to the San Juans burn silver iodide over a flame, and wind currents carry the smoke into passing storm systems, where the particles attract water vapor that crystallizes to form snowflakes.

Buyers Ten Colorado ski areas have used weather modification in recent years, including Vail, Beaver Creek, Breckenridge, Keystone, Telluride, Winter Park, and Crested Butte.

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Price Tag About $4.8 million since 2005 (including this season), paid for by ski resorts and agencies such as the state water conservation board, local water districts, and downstream states hoping for increased water runoff.

Payoff Studies suggest cloud seeding can add an extra inch or two of snow per storm—about 10 percent more powder annually in the northern and central mountains.

Fine Print The National Institutes of Health considers silver iodide toxic. But according to Colorado State University atmospheric science professor William Cotton: “It’s such a small amount that it’s not likely to have negative effects.”