Tornado

A tornado is a violently rotating column of air which is in contact with both a cumulonimbus cloud base and the surface of the earth. Tornadoes can come in many sizes, but are typically in the form of a visible condensation funnel, with the narrow end touching the earth. Often, a cloud of debris encircles the lower portion of the funnel.

Most tornadoes have winds of 110 mph (175 km/h) or less, are approximately 250 feet (75 meters) across, and travel a few miles (several kilometers) before dissipating. However, some tornadoes can have winds of more than 300 mph (480 km/h), be more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 kilometers).

Tornadoes have been observed on every continent except Antarctica; however, most of the world's tornadoes occur in the United States.