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What is a tornado?

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Quick answer

A tornado is a violently rotating column of air that reaches from a thunderstorm down to the ground. Though small compared with a hurricane, a tornado packs the fastest winds on Earth and can destroy almost anything in its narrow path.

Key things to understand

  1. Tornadoes form from powerful thunderstorms when warm, moist air meets cold, dry air and winds set the air spinning.
  2. A rotating updraft can tighten into a funnel; when it touches the ground, it becomes a tornado.
  3. They're usually a few hundred metres wide and last minutes, but the strongest have winds over 480 km/h.
  4. Strength is rated on the Enhanced Fujita (EF) scale, EF0 to EF5, based on the damage caused.
  5. 'Tornado Alley' in the central United States sees more tornadoes than anywhere else on Earth.

People also ask

What's the difference between a tornado and a hurricane?
A tornado is small and short-lived, forms over land from a thunderstorm, and can have the fastest winds on Earth. A hurricane is vast, forms over warm oceans, and lasts for days.
How are tornadoes measured?
On the Enhanced Fujita (EF) scale from EF0 to EF5, which estimates wind speed from the damage left behind rather than measuring it directly.
Where do tornadoes happen?
They can occur on most continents, but are most common and intense in the central US ('Tornado Alley'), where the right air masses regularly collide.

Part of the guide: Water & Weather Phenomena →