What is a tornado?

A tornado is a violently whirling column of air extending from the clouds to the ground. To be called a tornado, it must touch both clouds and ground; otherwise, it is simply a kind of cyclone. Tornadoes almost always extend from thunderstorm clouds called cumulonimbus clouds.

Most tornadoes travel at speeds up to 113 kph (70 mph), with the average speed being 48 kph (30 mph). The speed of the rotating winds of a tornado range from 104 kph (65 mph) to over 400 kph (250 mph).

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