The tornado is a vortex atmospheric disturbance of great intensity but of limited dimension accompanied by violent winds, contrary to thehurricane. It is the most violent and destructive meteorological phenomenon, with gusts of more than 300 km/h, which can even reach more than 700 km/h in the most extreme cases. Nevertheless, its geographical extent and its duration of life are weak.
Formation of tornadoes
The tornado begins near an updraft of a thunderstorm. This is why it is generally preceded by violent rains. Forms a cloud column in the shape of cone overturned or funneled at the base of a cloud (a cumulonimbus) to the ground. The low end gradually descends to the ground, dragging debris upwards in its path.
It then moves according to the movement of the cloud from which it was generated. Often it forms zigzags, or at least a curved trajectory, at a speed average of 50 km/h, sometimes more. It tears off almost everything in its path to the point of leaving the stigmata of its course on a reduced space. The difference of pressure inside and outside the whirlwind helps to amplify the damage, due to the call ofair generated.
Finally, after a few minutes, the cone rises gradually towards the cloud and disappears, letting calm return.
Rating of tornadoes: the Fujita scale
A tornado is classified according to its intensity, on thefujita scale, which goes from F0, with winds of less than 115 km/h, up to F5, with winds of more than 420 km/h, capable of destroying everything in their path. There are four intermediate categories.
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