The word tornado is from the Spanish word tronada which means "thunderstorm" It is a violent, dangerous, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud. Cumulonimbus cloud is a type of cloud that is tall, dense, and involved in thunderstorms and other intense weather. It is a result of atmospheric instability.

    Tornadoes come in many sizes but are typically in the form of a visible condensation funnel. It is a funnel-shaped cloud of condensed water droplets, associated with a rotating column of wind and extending form the base of a cloud. This funnel's narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds, between 64 km/h and 179 km/h.

    Although tornadoes have been observed on every continent except Antarctica most occur in the United States. They also commonly occur in Southern Canada, South-Central and Eastern Asia, East Central South America.

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