Tornadoes

A tornado is a violently rotating column of air that extends from the base of a thunderstorm down to the ground. It is among the most intense of all weather phenomena, capable of extremely high wind speeds within a narrow path. Tornadoes are usually visible as a funnel-shaped cloud filled with condensation, dust and debris, though they vary widely in size and strength. Most are relatively small and brief, but the strongest can cause severe destruction along their track.

Tornadoes form within powerful thunderstorms, particularly where warm, moist air at low levels meets cooler, drier air above, and where winds change speed and direction with height. This combination can set the air rotating; under the strong updraft of a severe storm, that rotation may tighten and reach the ground as a tornado. They are most frequent in regions where such air masses regularly collide, but they can occur in many parts of the world. Related events include waterspouts, which are tornado-like vortices over water.

The intensity of a tornado is commonly rated after the fact from the damage it causes, using a scale that ranks storms from weak to violent. Meteorologists use weather radar to detect the rotation within storms and issue warnings, giving people time to take shelter. Because tornadoes are small and develop quickly, precise prediction remains difficult, so prompt warnings and protective action are the main defences against them. These storms are distinct from hurricanes and tropical cyclones, which are far larger systems forming over warm oceans.

Frequently asked questions

What conditions produce tornadoes?

They typically arise in severe thunderstorms where warm, moist air meets cooler, drier air and winds change with height, setting the air rotating.

How is a tornado's strength measured?

Tornado intensity is usually estimated from the damage left behind, using a scale that ranks storms from weak to violent based on observed effects.

How are people warned about tornadoes?

Weather radar can detect rotation inside storms, allowing forecasters to issue warnings so people can take shelter before a tornado reaches them.