Science & Space
Tornado
A violently rotating column of air in contact with the ground and the base of a thunderstorm, capable of very strong winds and localized destructive damage.
A tornado is a violently rotating column of air that extends from the base of a thunderstorm to the ground.
Most strong tornadoes form from certain severe thunderstorms (often supercells) when wind shear and updrafts produce a concentrated rotating updraft that tightens into an intense vortex.
Quick facts
- Definition: By meteorological definition, a tornado is a violently rotating column of air in contact with both a thunderstorm (cumuliform cloud base) and the ground; a visible condensation funnel is common but not required to confirm a tornado. (Sources: NWS, SPC, NSSL).
- Common origin: Many strong tornadoes form from supercell thunderstorms when wind shear creates a horizontal rotation that is tilted and stretched by a storm’s updraft into a vertical, concentrated vortex (a mesocyclone and subsequent tornadogenesis). (Sources: SPC, NSSL, UCAR).
- Intensity measurement: Tornado intensity is inferred from damage using scales such as the Fujita and Enhanced Fujita (EF) scales rather than direct, sustained wind measurements inside most tornadoes. (Source: NOAA/NOAA Science Council).
- Geographic distribution: Tornadoes occur worldwide, though the United States experiences the largest number reported each year; other countries (Canada, parts of Europe, Bangladesh, Australia, etc.) also record tornadoes. (Sources: NOAA, scientific summaries).
- Warnings and confirmation: The National Weather Service’s Storm Prediction Center issues tornado watches (conditions favorable) and local offices issue tornado warnings (tornado observed or indicated by radar); confirmation of a tornado may be made by funnel or by a debris cloud at the surface even if the condensation funnel is not visible. (Sources: SPC, NWS, NSSL).
A surprising fact
A tornado can be present even when no funnel is visible—meteorologists can confirm a tornado by observing a debris cloud touching the ground beneath the storm even if the condensation funnel does not reach the surface. (Source: NWS).
