How do tornadoes damage homes?
As a tornado or other storm system passes over a building, low pressure can tug a roof upward, scientists say. And the winds to the side of it exert a high pressure that pushes roofs up from the sides, said Jewel Barlow, a professor of aerospace engineering at the University of Maryland College Park, who directs the Glenn L. Martin Wind Tunnel at the university. When those forces surpass the force exerted by the weight of the roof, the structure flies up and is swept away by wind currents, he said. “If you watch the leaves fly by, it’s the same thing at a lower speed,” Barlow said. Most roofs are held down by nails and the force of their own weight, making it relatively easy for a tornado to flip them into the air, he said. In Florida, laws were passed following Hurricane Andrew in 1995 that require roofs to be strapped to the walls and foundations of new homes, he said. The shape of roofs can make some easier to pry up than others, Barlow said. “Because most roofs are peaked, there is
