Boom Time in the Vineyards

Bordeaux's Château d'Issan fires cannons as storms approach to prevent hail from prematurely crushing its grapes.

This illustration of a hail cannon appeared in a French newspaper circa 1900.

Leemage/UIG via Getty Images

After golf ball–sized hailstones battered vines at Château d’Issan in Bordeaux for two years in a row, managing director Emmanuel Cruse was in the market for something—anything—that might protect his grapes. That’s when he decided to try a device that promises to prevent hailstones from forming, Bloomberg Markets reports in its April 2015 issue. Different types of hail cannons, as they’re known, have been around for more than a century in France, even though it’s far from clear they do what they’re supposed to do.

“We had to do something,” Cruse recalls. “Storms destroyed 70 percent of our grapes in 2008 and 2009. Each of those years, we produced less than 6,000 cases of wine,” compared with the typical 19,000 cases. The total financial loss to this third-growth estate in the Margaux appel­lation was almost €3 million ($3.4 million), Cruse says. Insurance paid out just one-fifth of that.

So Cruse invested €150,000 in two cannons that are now permanently installed in his vineyards. They’re linked to a radar system that automatically sets them off when it detects an approaching storm. A blast—a loud boom followed by a reverberating whistling sound—goes off every four to six seconds. Cruse gives his neighbors cases of wine to make up for the noise pollution.

Hailstones develop in large, high clouds when warm storm updrafts suck rain into the upper air’s freezing temperatures. Supercooled drops collect around tiny ice crystals or bits of dust and become big enough to fall without melting.

While the original hail cannons fired gunpowder-fueled blasts skyward, modern versions work off of a charge of acetylene gas and air. They generate a series of high-velocity vortex shock waves inside storm clouds, says Newton Wimer, whose California-based Newton Systems International makes the devices. The moisture in the cloud falls as a kind of benign slush or rain—at least that’s the claim.

Brant Foote, director of the Research Applications Laboratory at the National Center for Atmospheric Research in Boulder, Colorado, who’s spent his career studying hail, is dubious. He says of the cannons, “There’s zero scientific evidence that they’re effective.” He’s also skeptical of an alternative technology that shoots silver iodide into clouds to create smaller hailstones that will melt as they fall. That practice didn’t prevent Burgundy vineyards from being hammered last summer. Winemakers there are talking about trying the anti-hail nets that are used in Argentina.

Is Cruse convinced the technology behind his booming cannons is sound? He says it’s possible his vineyards have been hail-free for five years—even as close neighbors have been hit—simply due to luck. And he still pays €30,000 a year for insurance “just in case,” he says. That said, he’ll have his hail devices fueled up and ready when storm season comes again.

This story appears in the April 2015 issue of Bloomberg Markets.