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Tornado Cloud Types

Spring and summer in the United States brings tornado season to the parts of the country east of the Rocky Mountains. For the Midwest and plains states, it is a dangerous time. A tornado is defined as a violently rotating column of air extending from thunderstorm to ground. Different cloud types in the atmosphere with thunderstorms identify tornadoes.

Funnel Clouds
- The funnel cloud is the distinctive signature of a tornado. The wind within the funnel cloud is the cause of most of the destruction, with the capability of exceeding 250 mph. This wind knocks down structures and stirs up debris. The debris then causes damages of its own by striking other structures.
Cumulonimbus
- Warm air lifts up into the atmosphere. The air cools and the dew point is reached, resulting in condensation. The formation of a cumulus cloud follows. If the atmosphere is unstable and the air continues to be uplifted then the cumulus cloud will become a thunderstorm. As conditions continue and the air uplifts, the cumulus cloud transforms into a cumulonimbus cloud. Cumulonimbus clouds reach heights of 20 kilometers and produce severe weather, including tornadoes.
Rotating Wall Cloud
- In many cases, "supercell" thunderstorms create tornadoes. One defining characteristic of this type of thunderstorm is rotation. This rotation normally occurs on the south side of the storm. To the observer, the low-hanging rotating clouds may or may not be visible due to rain. Watch for very black sky to accompany the rotating wall cloud.
Waterspout
- Waterspouts form over any type body of water.
  
  Warm waters in the Gulf of Mexico and off the southeastern United States coast provide conditions conducive for waterspouts. Waterspout is a name for a tornado cloud over water. In the western United States, waterspouts form in late fall and winter, which is unusual for tornadoes. Occasionally waterspouts move from water to land and are transformed into tornadoes.

Nature