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.

Read more about 'Tornadoes'

Visible clues of a tornado can be difficult to spot as some tornadoes never form a visible funnel. But dark green skies, walls of clouds with large hail and a loud roar similar to a freight train are good indicators that conditions are ripe for a tornado.
In the event of a tornado, it’s best to move to either a basement or the lowest possible floor in a building. If a basement is not available, an interior room of the building that is away from windows, such as a hallway or bathroom, is the second best option.
(Text by Noel Kirkpatrick)
(Photo: ya.zan)

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