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6. Secondary Circulation
Tornadoes have the power to lift very large objects
Tornadoes develop from special types of thunderstorms known as "supercells". In such storms low level rotation, called a "mesocyclone", forms a narrow downwards extending funnel cloud. The low pressure in the centre of this spinning funnel allows air to rush in and expand and cool. Once the funnel hits the ground the strong winds start to pick up dirt and debris. Amazingly large objects can be picked up and dropped several metres away. The diameter of tornadoes is typically 100 m and they last on average for a few minutes. In that time they typically travel up to 1 km, with wind speeds generally around 65 m/s, occasionally reaching above 100 m/s.
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How long do tornadoes last and what wind speeds do they generate?