Science
How does a tornado form?
A tornado forms when a thunderstorm's rising warm air meets winds blowing at different speeds and directions, setting the air spinning. That spin can tighten into a violent, funnel-shaped column stretching from cloud to ground.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a tornado works.
Step by step
- 1It starts with a strong thunderstorm and warm, moist air rising fast.
- 2Winds changing speed and direction with height (wind shear) start the air rotating.
- 3The rotation can tilt upright and tighten into a spinning column inside the storm.
- 4If that column reaches the ground, it is a tornado.
- 5The most powerful tornadoes come from rotating storms called supercells.
Frequently asked questions
- What's the difference between a tornado and a hurricane?
- A tornado is small and short-lived, forming over land from a single storm; a hurricane is a vast ocean storm system hundreds of kilometres wide that lasts days.
- Why do tornadoes form in 'tornado alley'?
- Places like the central US mix warm, moist air from the south with cool, dry air from the north, creating the instability and wind shear tornadoes need.
- How are tornadoes rated?
- By the damage they cause, on the Enhanced Fujita (EF) scale from EF0 to EF5, which estimates wind speed from the destruction left behind.