What the hail? Farmers aim sonic cannons at storm clouds

A thunderous boom from a 20-foot cannon echoes over John Diepersloot’s apricot and peach orchards, a weapon the farmer hopes can save his trees from storms by breaking up hailstones before they can form.

Hail cannons, which switch on when storms are approaching, are the latest high-tech device aimed at protecting crops from the volatile weather that hits California’s agricultural heartland, where a single hailstorm or freeze can destroy a crop -- and a local economy -- overnight.

Though scientists say no significant study has proved the devices’ effectiveness, a small group of farmers in the San Joaquin Valley and across the country is putting faith -- and tens of thousands of dollars -- into hail cannons.

“The first year I had them, there was a storm where I saw my neighbor’s fields had damage and I didn’t,” said Diepersloot, who has bought 24 cannons to use throughout his 1,200-acre Kingsburg farm. “It’s the science of nature.”

With the 2007 storm season approaching, Diepersloot’s workers are preparing to wage war on the weather.

The huge, conical machines click on automatically when a Doppler radar signal -- the indicator meteorologists use to detect hurricanes -- senses a storm.

Within seconds, they emit a deafening, electronic blast, repeated every six seconds.

As the sound waves rise from the cannon and ripple into the sky, they disrupt airborne water droplets poised to become hailstones and cause the water to fall as rain or slush, the cannon’s manufacturers say.

But scientists dispute their claims.

“It’d have to be something pretty major to upset hail,” said Charles Knight, a senior scientist with the National Center for Atmospheric Research, a Boulder, Colo.-based nonprofit organization.

“If you exploded an atomic bomb in a cloud, that might do something,” Knight said.

At $50,000 to $70,000 each, the cannons aren’t a cheap fix. But losses from hailstorms and freezes can be even more costly.

California orange and lemon farmers lost an estimated $700 million from a four-day freeze in 1999 that destroyed 80% of California’s navel and Valencia crops.

Hailstorms don’t kill the fruit, but they, too, take an economic toll.

Blemished fruit usually sells for about 60% of an unmarked crop’s value, farmers said, and sometimes cannot be sold at all.

“In the past, the only way to deal with hail was to have insurance, but that got too expensive,” Diepersloot said. “No one wants scarred fruit.”

In the last decade, farmers in Colorado, Nebraska, Michigan and Ohio have bought the machines, as have car dealerships in Mississippi seeking to protect their lots.

Though the cannons have yet to be widely adopted in the San Joaquin Valley, they’re already well known -- their boom can be heard 12 miles away.

Depending on a storm’s intensity, the sound from one cannon can cover up to 240 acres, something Diepersloot said has rubbed some of the orchard’s rural neighbors the wrong way.

“There’s no negative to it ... other than noise,” Diepersloot said.

Most growers can’t afford such gadgets, said Harry Andris, a tree fruit expert for the University of California Cooperative Extension office in Fresno County.

“There just isn’t a lot of technology that we can use to alter the weather. Some of the things that farmers try aren’t that effective,” Andris said. “Unfortunately, you have to buy them to try them.”