THE first requisite of tornado formation is a violent updraught of moist air. In a paper on the nor'westers in Bengal, which will be published shortly, it is being shown from a large number of ...

Tornado formation in the U.S. requires a ... La Niña alter the natural flow of weather ... to violent tornado occurrences in the U.S. noted in Chart 3, tornadoes can—and do ...

Watch "Deadliest Tornadoes" streaming online to learn why the 2011 tornado season in the U.S. was so extreme. Photo Credit: 2007 Elie Manitoba tornado / Wikimedia Commons (CC-BY-SA-2.5,2.0,1.0 ...