A tornado touches down near Elie, Man., on June 22, 2007. (Wayne Hanna/Canadian Press)
"The worst tornadoes are the most violent storms on earth" - Environment Canada.
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What:
Tornadoes occur when warm, humid air meets cool, dry air. When the two meet, the cool air traps the warm air, and keeps it from rising. The trapped air is further warmed by radiant heat of the earth's surface. Trapped, the warm air rotates horizontally and finally gains enough strength to punch through the ceiling of cool air. The cool air then begins falling quickly, forcing more warm air upward. Often, this swiftly falling air known as a downburst is mistaken for a tornado when it strikes the earth's surface. Indeed, downbursts can be just as destructive as some tornadoes, and can generate a 200-km/h blast of tree-flattening wind.
The swiftly moving air begins to spin like a top as it moves. If it spins fast enough, a funnel forms. When the funnel touches the ground, it is referred to as a tornado.
Damage:
According to Environment Canada, there are an average of 80 tornadoes each year in Canada, causing two deaths and injuring 20. Damage runs into the millions.
![](/web/20080911042634im_/http://www.cbc.ca/news/background/forcesofnature/gfx/tornado1.gif)
Tornadoes are measured in Canada using the Fujita scale, developed by Chicago researcher Dr. T. Theodore Fujita. The classifications are as follows:
![](/web/20080911042634im_/http://www.cbc.ca/news/background/forcesofnature/gfx/tornado2a.gif)
Environment Canada analysts rated the tornado that hit Elie, Man., on June 22, 2007, as the strongest documented twister in the country's history.
It is the only officially confirmed tornado in Canada to be rated F-5 on the Fujita scale, with wind speeds estimated at 420 to 510 kilometres an hour.
The twister was on the ground for more than 30 minutes, Environment Canada officials said. It travelled five kilometres, creating a 300-metre swath of damage through the town of 550 people. No one was killed or seriously hurt but 19 people were left homeless.
Tornado game plan:
According to most weather authorities, including Environment Canada, your best option in the event of a tornado is to head for your basement. If you don't have one, get in a closet or small room near the center of the building, away from windows or doors. Environment Canada suggests getting into the bathtub and covering yourself with a mattress. Otherwise, get underneath a sturdy piece of furniture which can help shield you from falling or flying debris.If you're caught outdoors or in a vehicle, find the nearest ditch and lay low with your head shielded by your arms.
If you're in a mobile home, get out and find a permanent shelter (preferably with a basement) or find a ditch. According to Environment Canada, more than half of all tornado deaths occur in mobile homes.
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