But when it comes in the form of fist-sized balls of ice known as hail, water's more than a menace. It can damage and even destroy crops.
That's where the Western Kansas Weather Modification Program and other cloud-seeding operations across the western U.S. come in. The WKWMP is among about 10 programs that tinker with the weather -- either by trying to cut the size of hail or boost rainfall and snowpack. They do it largely by shooting up storm clouds with silver iodide or dry ice mixtures.
Other countries also have used or considered using weather modification. The United Arab Emirates has investigated cloud seeding to help increase rainfall. China has announced plans to use cloud seeding to manage rainfall during the 2008 Olympics, and Indonesia has used it to try to fight fires.
Cloud seeding has a host of critics, from those who say there is no good science to support claims that it works to others who raise concerns about the possibility that it actually may cause less rain and harm the environment.
But as water supplies show signs of stress around the globe and insurance companies add up hail damage payouts, weather modification programs persist.
"What's beginning to happen is that worldwide, people are realizing that water, especially fresh water, is a very precious resource, and we need to do what we can to increase the availability of that resource," said Bruce Boe, director of meteorology for Weather Modification Inc., a Fargo, N.D.,-based company that has been seeding clouds since the 1960s. Weather Modification Inc. has contracts in the U.S., Africa, southeast Asia and Canada, where Weather Modification Inc. does business with insurance companies.
"They'll say, 'We paid out $500, $600 million in claims on hail damage, and the forecast is for more hail storms, so we want you to come in for a couple million dollars and take care of the hail,"' Boe said.
Cloud seeding was developed after World War II to try to increase rainfall. The theory is that the silver iodide, which has a structure that resembles ice, creates raindrops in the clouds, increasing precipitation and reducing moisture for hail formation.
In the U.S., weather modification programs are largely run by individual states and counties. But a measure before the U.S. Senate would allocate $10 million a year to establish the Weather Mitigation Advisory and Research Board, which would develop policy and research weather modification programs.
Kansas started its program in 1975. The Western Kansas Weather Modification Program now covers about 8,000 miles and is used about 85 percent of the time for hail reduction. The program, which receives state and local funding, was briefly extended into northwest Kansas in the late 1990s. But residents became concerned that cloud seeding may have been reducing their rainfall amounts and voted the program out.
The WKWMP operates from April through September with four planes. Program manager Walt Geiger monitors the weather from a radar station at the tiny Kearny County airport in Lakin. When he sees a storm developing, one with "lots of strong vertical action" that could be a hail producer, Geiger notifies the pilots, who then head into the storms in their single-engine planes, armed with nerves and bayonet-sized canisters of silver iodide.
A 1998-1999 study of the WKWMP found that while there was a statistically significant reduction in hail that year, there was no evidence to support the program's attempts to increase rainfall.
The science behind cloud seeding, while "excellent at the microscopic level," doesn't translate too well outside the lab, says Terry Kastens, professor of agriculture economy at Kansas State University, which conducted the study.
"The practicality of whether you can actually get enough of the iodide in the air is a really big question," says Kastens. "A lot of time we joke it's like shooting a pea shooter at the clouds."
David Brenn, WKWMP's director, discounts naysayers. He says he has seen the benefits of hail reduction efforts. He also says at least one insurance company has expressed interest in partnering with WKWMP.
But Mike Standley, whose family has farmed in southwest Kansas for about a century, says he's concerned that cloud seeding may be costing him some precious rain. It has been a long time since he has seen regular summer afternoon thunderstorms on his land, says Standley, 30.
"Now the day when we have one little storm popping up, they'll be flying up and around it, and it just seems to fizzle out," he says.
Standley says he would like to see solid proof that cloud seeding works. With 14 to 19 inches of precipitation a year, he just can't spare the moisture.
"I can raise crops with hail," he said. "But I can't raise crops with no moisture."