A tornado is a violently rotating column of air extending from a cumulonimbus cloud to the ground. Tornadoes are the most intense atmospheric vortices on Earth, with wind speeds ranging from 100 km/h (EF0) to over 480 km/h (EF5) on the Enhanced Fujita scale. Their path is typically narrow (100–500 m wide) but can reach 2 km in extreme cases, with path lengths from a few hundred metres to over 100 km.
Most significant tornadoes are spawned by supercell thunderstorms, where a persistent rotating updraft (mesocyclone) tightens into a funnel. The process begins with wind shear creating horizontal rotation that is tilted into the vertical by the storm's updraft. As the rotating column narrows, conservation of angular momentum accelerates the winds — like an ice skater pulling in their arms. The visible funnel is a condensation funnel; the actual tornado can be wider, marked by debris at the base.
The United States experiences the most tornadoes worldwide (~1,200/year), concentrated in "Tornado Alley". However, tornadoes occur on every continent except Antarctica. In Europe, roughly 300–400 tornadoes are reported annually, with hotspots in northern France, Germany, Poland, and northern Italy. Spain records approximately 10–15 tornadoes per year, mainly in the Ebro valley, Catalonia, Balearic Islands, and Andalusia. The TORRO scale is used in Europe alongside the Enhanced Fujita scale. Early detection via Doppler radar (mesocyclone signatures) provides critical lead time for warnings.