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. Other areas which commonly experience tornadoes include New Zealand, western and southeastern Australia, south-central Canada, northwestern and central Europe, Italy, south-central and eastern Asia, east-central South America, and Southern Africa.

Read the rest of this article: http://en.wikipedia.org/wiki/Tornado

_______________________________ Today's selected anniversaries:

1626: Peter Minuit bought Manhattan in exchange for trade goods valued at 60 guilders. (http://en.wikipedia.org/wiki/Peter_Minuit)

1822: Ecuadorian War of Independence: Troops led by Antonio José de Sucre secured the independence of Quito from Spain in the Battle of Pichincha. (http://en.wikipedia.org/wiki/Battle_of_Pichincha)

1883: The Brooklyn Bridge, at the time the longest suspension bridge in the world, was opened. (http://en.wikipedia.org/wiki/Brooklyn_Bridge)

1941: World War II: The German battleship Bismarck sank the British battlecruiser HMS Hood in the Battle of the Denmark Strait. (http://en.wikipedia.org/wiki/German_battleship_Bismarck) (http://en.wikipedia.org/wiki/HMS_Hood_(51))

1962: Project Mercury: American astronaut Scott Carpenter orbited the Earth three times in the Aurora 7 space capsule. (http://en.wikipedia.org/wiki/Scott_Carpenter)

_____________________ Wikiquote of the day:

Freedom of expression is the matrix, the indispensable condition, of nearly every other form of freedom. -- Benjamin N. Cardozo (http://en.wikiquote.org/wiki/Benjamin_N._Cardozo)