So far this year, there have been nearly 1,200 tornadoes in the U.S. That's close to twice the usual number — and it comes as something of a surprise to the scientists who study them.
Copyright 2011 NPR
So far this year, there have been nearly 1,200 tornadoes in the U.S. That's close to twice the usual number — and it comes as something of a surprise to the scientists who study them.
Copyright 2011 NPR