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 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 visible condensation funnel. It is a funnel-shaped cloud of condensed water droplets, associated with a rotating column of wind and extending from 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 to 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, and South America.

What is the text mostly about?
a. The cause and the danger of tornado
b. The effect and the size of tornado
c. The kinds and the effect of tornado
d. The information and the shape of tornado

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