Tornadoes What is a tornado?

A tornado is a localized violently destructive windstorm over land, and formed by a funnel-shaped cloud extending toward the ground.

Quick Facts:

Some tornadoes may form during the beginning of big thunderstorms.

Tornadoes may appear almost invisible until dust and debris are picked up.

Occasionally, two or more tornadoes may happen at the same time.

When associated with hurricanes, tornadoes usually don't have thunder storms.

Only 2% of tornadoes are violent ones.

69% of tornadoes are weak ones.

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The United States gets about 1000 recorded tornadoes every year.

Rank
States
Date
Time
Dead
Injured

1
MO,IL,IN
3-18-1925
1:01pm
695
2027
2
LA,MS
5-7-1840
1:45pm
317
109
3
MO,IL
5-27-1896
6:30pm
255
100
4
MS
4-5-1936
8:55pm
216
700
5
GA
4-6-1936
8:27am
203
1600
6
TX,OK,KS
4-9-1947
6:05pm
181
970
7
LA,MS
4-24-1908
11:45am
143
770
8
WI
6-12-1899
5:40pm
117
200
9
MI
6-8-1953
8:30pm
115
844
10
TX
5-11-1953
4:10pm
114
597



Types of tornadoes:

  • Multiple Vortex

  • Waterspout

  • Land spout

  • Gustnado

  • Dust devil

  • Fire whirls and steam devils


How do tornadoes form?

Many tornadoes develop in a special Type of thunderstorm called a "supercell". A layer of warm humid air forms near the ground along with strong south winds. In the upper atmosphere lie colder air and strong west or southwest winds. the temperature and moisture differences between the surface and upper levels create instability, which is one of the necessary factors for the formation of tornadoes. The alteration of the speed and height of the wind is called "wind shear". The wind shear helps the development of rotation, which forms the tornado. A lifting of the air is the beginning of the development of very violent thunderstorms that eventually help the final formation of the tornado. When the updraft starts rotating, the tornado arises.

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Funnel Cloud

A funnel cloud is a funnel shaped cloud made of condensed water droplets associated with a rotating column of wind and extending from the base of a cloud but not touching the ground. A funnel cloud is usually visible as a cone shaped protuberance from the base of a cloud. Funnel clouds form most often when associated with supercell thunderstorms. If a funnel cloud touches the ground it becomes a tornado.


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Damage


Tornadoes are very powerful. They destroy houses, buildings, and entire towns. The Fujita scale ranks tornadoes based on how much damage they cause. It ranks from F0-F5. Tornadoes can lift cars and fling them up to a 1/2 mile away. F2s and F3s can tear off roofs. The deadliest outbreak occurred or April 3rd 1974, when a two-day super outbreak of 147 tornadoes killed 308 people in 13 states. Tornadoes are very dangerous.



Sources

http://www.cln.org/themes/tornadoes.html


http://www.nssl.noaa.gov/edu/safety/tornadoguide.html