Cloud seeding

Silver iodide has been the dominant ingredient for cloud seeding in the West, but it doesn't work so well in warm temperatures.

Cloud seeding involves using planes and ground-based equipment to put silver iodide into clouds when weather conditions are right. Colorado, Utah and Wyoming have all expanded their cloud-seeding programs in recent years.

The funding comes as key reservoirs on the Colorado River hit record lows and booming Western cities and industries fail to adjust their water use to increasingly shrinking supplies.

Each winter, anxious water managers, farmers and city leaders in the American Southwest turn their eyes toward the snowy peaks of the southern Rocky...