Tornadoes typically form within supercell thunderstorms, where a rotating updraft called a mesocyclone develops. Wind shear — winds changing speed and/or direction with height — creates a horizontal spinning tube of air, which the storm's updraft tilts into a vertical rotating column. As this column tightens and intensifies near the ground, the visible funnel cloud appears: a rapid pressure drop and cooling in the vortex core causes water vapor to condense, while a swirling cloud of dust and debris is kicked up where the vortex meets the surface. Meteorologists rate tornado intensity using the Enhanced Fujita (EF) scale, based on surveyed damage, and the central United States — nicknamed "Tornado Alley" — sees some of the highest tornado frequency on Earth due to the collision of warm Gulf moisture and dry, cold continental air.

• EF0: roughly 105–137 km/h; EF5: over 322 km/h wind speeds
• Average path length is only a few kilometers, often lasting just minutes
• Funnel diameter ranges from tens of meters to, rarely, over 1.6 km wide
• Central core pressure can drop 100+ hPa below the surrounding ambient pressure
• Most tornadoes rotate cyclonically (counterclockwise in the Northern Hemisphere), though this is a statistical tendency, not an absolute rule
• Debris clouds at the base are often darker and denser than the condensation funnel above
• Tornado Alley (US central plains) records some of the world's most frequent, intense tornadoes