A tornado is a violent atmospheric wind storm that extends from a thunderstorm to the ground in a funnel shape. Very often tornadoes form out of supercell thunderstorms, which are storms that last for a number of hours, have a rotating updraft of wind and have a hook or pendant shape on radar.

 

The updraft of wind in these weather systems contributes to the formation of a tornado. Wind that is closer to the ground moves at a slower speed in one direction and gets caught in a storm’s updraft that is moving faster and in the opposite direction. This is called a wind shear. The updraft tilts the wind closer to the ground to a vertical angle resulting in a column of rotating air that forms tornadoes.