How do tornadoes form?
The truth is that National Weather Service don't fully understand. The most destructive and deadly tornadoes occur from super cells, which are rotating thunderstorms with a well-defined radar circulation called a mesocyclone. (Supercells can also produce damaging hail, severe non-tornadic winds, unusually frequent lighting, and flash floods.) Tornado formation is believed to be dictated mainly by things which happen on th storm scale, in and around the mesocyclone. Recent theories and results from the VORTEX2 program suggest that once a mesocyclone is underway, tornado development is related to the temperature difference across the edge of downdraft air wrapping around the mesocyclone. Mathematical modeling studies of tornado formation also indicated that it can happen without such temperature patterns; and in fact, very little temperature variation was observed near some of the most destructive tornadoes in the history on May 3, 1999.

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1. What is a tornado?
2. When are tornadoes most likely?
3. Where do tornadoes occur?
4. How do tornadoes form?
5. What is straight-line wind?
6. What is a downburst?
7. How many tornadoes occur in the U.S. each year?