Study reveals mystery of tornadoes spawning more twisters

The research was carried out by a team at Columbia University who looked at the most extreme outbreaks and tornadoes above the minimal wind rating. "Something's up," said applied physics professor Michael Tippett, lead author of the study in the Science journal. Unlike other spikes of extreme weather in recent years, Prof Tippett and his colleagues found no obvious link to man-made global warming.