Tornadoes may form from the ground up, rather than the top down.
That could sound counterintuitive. Many people may picture a funnel cloud emerging from the bottom of a dark mass of thunderstorms and then extending to the ground, atmospheric scientist Jana Houser said December 13 in a news conference at the American Geophysical Union meeting.
Scientists have long debated where the wind rotations that lead to twisters in these thunderstorms begin. Now Houser, of Ohio University in Athens, and her colleagues have new data that upend this “top-down” idea of tornadogenesis.