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The Monday storm that pounded Calgary with hail the size of golf balls would have been even more severe if cloud seeding planes hadn't been in the sky earlier in the day, says an official with the company that flies the aircraft.

Just before the hail hit the city, Weather Modification Inc. had two airplanes in the air, seeding the clouds with shots of silver iodide, which shrinks the ice stones, said Tom Walton, the company's field program manager.

"We were right in and around, east, west, north and south of Calgary," Walton said. "We were flying for approximately one hour prior to the development of the storm. Then, we stayed with it for the duration in and around Calgary."

The hailstorm dented countless vehicles and damaged homes and businesses, including the glass rooftop greenhouses at the University of Calgary.

The 15-year-old Weather Modification Inc. is paid by a consortium of insurance firms, which banded together as the Alberta Severe Weather Management Society in an effort to reduce the cost of claims associated with hail damage.


Cloud seeding planes were in the skies on Monday when Calgary got pounded with huge hail stones. (CBC)

Three meteorologists in Olds monitor weather systems from roughly Lacombe to High River, sending the four planes up — two from Calgary and two from Red Deer — when they spot a potential hailstorm.

"What we're trying to do is locate areas of what we call new development," said Walton.

"All we can do is reduce and minimize. We do not prevent hail."

Calgary's unique geography makes cloud seeding more of an art than a science, said chief pilot Jody Fischer.

"One of the unique things here is the city is so close to the mountains that the storms, when they come off the mountains, they're right there," Fischer said. "So, you've got to be there earlier than a lot of other places."