How does a tornado form?
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A tornado builds up within minutes and, in relation to its brief duration, is more destructive than a hurricane. Topics Online explains how a tornado forms.
On Monday, 20 May, a one-and-a half kilometre wide tornado tore through the suburbs of Oklahoma City gouging a 30 km long by 2 km wide corridor of destruction out of the landscape. With wind speeds of over 320 kilometres per hour, the tornado has been classified as the most powerful possible, known as an EF-5 on the Enhanced Fujita scale. At local level tornadoes of this strength can wreak far more destruction than a hurricane. And they form suddenly. The people of Oklahoma had only 15 minutes to protect themselves against the approaching tornado. The tornado swept over the ground for over 40 minutes.
The formation of a spring tornado
In contrast to hurricanes, which develop from tropical storms over the sea in summer and autumn, these typical spring tornadoes usually develop over flat stretches of land. A region that is particularly threatened by tornadoes is the "Tornado Alley" in the Midwest of the USA, where the state of Oklahoma also lies. Warm and cold air masses collide here and form gigantic thunderstorm clouds, so-called super cells. The infographics below show how a tornado develops from a super cell.