Tornadoes are violently rotating columns of air that extend from a thunderstorm cloud down to the ground and can produce some of the strongest winds on Earth. They can destroy buildings, uproot trees, and hurl heavy objects through the air in a very short time.
What tornadoes are
- A tornado is defined as a rotating column of air in contact with both a cumuliform cloud base and the ground, often visible as a funnel cloud.
- Many tornadoes form from intense thunderstorms called supercells, although not all thunderstorms produce tornadoes and the exact formation process is still not fully understood.
How strong and big they can be
- Most tornadoes have wind speeds under about 110 mph and are a few hundred feet wide, lasting only a few miles on the ground.
- The most extreme tornadoes can exceed 200–300 mph, grow to more than a mile across, and carve paths over 50 miles long, causing catastrophic damage.
Where and when they happen
- Tornadoes occur on every continent except Antarctica, but the United States has the highest number, with roughly a thousand events in a typical year.
- In the U.S., many of the strongest tornadoes occur in “Tornado Alley,” a region of the central Plains, and are most common in spring and early summer, typically in the late afternoon and evening.
Danger and impacts
- In the U.S., tornadoes cause on the order of dozens of deaths and thousands of injuries per year, mainly from flying debris and collapsing structures.
- The most violent category, EF5 on the Enhanced Fujita Scale, represents tornadoes with winds over about 200 mph that can level well-built houses and large buildings and are responsible for a disproportionate share of tornado fatalities.
Other neat facts
- The average forward speed of a tornado is around 30 mph, but some move very slowly while others race along at highway speeds up to about 70 mph.
- Tornadoes can also form over water as waterspouts, can occur in clusters from the same storm, and can last from just a few seconds up to several hours in rare cases.
