For 28 years he has chased after and photographed extreme weather, and at last count had come face to face with 655 tornadoes. "It's the adrenaline," he explains. "The object is to get close and see the power and beauty and document it."

But there are ways to go about it that are safe—and ways that are definitely unsafe. "Think of the photographer looking to document grizzlies. You can approach and take a picture. But if you make a wrong move you can get killed."

As the director of Silver Lining tours, a company that specializes in extreme-weather travel, Hill spends about four months on the road. When I caught up with him by phone, he was running a tour and keeping