A tornado is a violently rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as twisters or cyclones, although the word cyclone is used in meteorology, in a wider sense, to name any closed low pressure circulation. Tornadoes come in many shapes and sizes, but they are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds less than 110 miles per hour (177 km/h), are about 250 feet (76 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (483 km/h), stretch more than two miles (3.2 km) across, and stay on the ground for dozens of miles (more than 100 km).

Various types of tornadoes include the landspout, multiple vortex tornado, and waterspout. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud. They are generally classified as non-supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes. These spiraling columns of air frequently develop in tropical areas close to the equator, and are less common at high latitudes. Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirls, and steam devil.

Tornadoes have been observed on every continent except Antarctica. However, the vast majority of tornadoes in the world occur in the so-called "Tornado Alley" region of the United States, although they can occur nearly anywhere in North America. They also occasionally occur in south-central and eastern Asia, northern and east-central South America, Southern Africa, northwestern and southeast Europe, western and southeastern Australia, and New Zealand. Tornadoes can be detected before or as they occur through the use of Pulse-Doppler radar by recognizing patterns in velocity and reflectivity data, such as hook echoes, as well as by the efforts of storm spotters.

There are several scales for rating the strength of tornadoes. The Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale. An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and assign a rating.

Read more about Tornado:  Etymology, Definitions, Intensity and Damage, Climatology, Detection, Extremes, Safety, Myths and Misconceptions, Ongoing Research

Other articles related to "tornado":

Tornado - Ongoing Research
... low-level mesocyclone and the stretching of low-level vorticity which tightens into a tornado, namely, what are the processes and what is the relationship of the environment and the convective storm ... Reliably predicting tornado intensity and longevity remains a problem, as do details affecting characteristics of a tornado during its life cycle and tornadolysis ... tornadoes still strike without a tornado warning being issued ...
Late-May 1998 Tornado Outbreak And Derecho - Spencer, South Dakota Tornado
... The Spencer, South Dakota tornado was the most destructive and second deadliest tornado in the history of the state ... It was also the fifth deadliest tornado of the year ... It began as a large, dust-cloaked tornado Northwest of Farmer, SD in Hanson County, concurrent with the demise of the "Fulton" tornado ...
Late-May 1998 Tornado Outbreak And Derecho
... The Late-May 1998 Tornado Outbreak and Derecho was a historic tornado outbreak and derecho that began on the afternoon of May 30 extending ... The initial tornado outbreak, including the devastating Spencer tornado, hit southeast South Dakota on the evening of the May 30 ... The Spencer tornado was the most destructive and second deadliest tornado in South Dakota history ...
1996 Southern Ontario Tornadoes
1 2 Southern Ontario's worst tornado outbreak of the decade came on Saturday April 20, 1996 ... The first tornado that touched down tore a 40 kilometre long path southeast of Owen Sound ... A second tornado touched down farther south and took a 60 kilometre track from Arthur to just southwest of Barrie ...
Late-May 1998 Tornado Outbreak And Derecho - Confirmed Tornadoes - May 30 South Dakota Event
... Dakota F0 W of Lake Preston Kingsbury 0002 unknown First tornado touchdown ... (3.2 km) This was a fairly large and dusty tornado that affected mostly open ground in rural areas ... It was the first tornado of the tornado family generated by the supercell that produced the Spencer tornado ...

Famous quotes containing the word tornado:

    The sumptuous age of stars and images is reduced to a few artificial tornado effects, pathetic fake buildings, and childish tricks which the crowd pretends to be taken in by to avoid feeling too disappointed. Ghost towns, ghost people. The whole place has the same air of obsolescence about it as Sunset or Hollywood Boulevard.
    Jean Baudrillard (b. 1929)