F5 tornado near Elie, Manitoba in 2007
photographer Justin Hobson, Wikimedia Commons
Tornados are a dangerous force of nature. With winds of over 350 kilometers (over 200 miles) per hour, tornadoes can flatten houses and lift cars off the ground.
Tornados form in the clouds of severe thunderstorms when warm air from the south meets cold air from the north.
Inside the thunderstorm, fast winds flow over slow ones creating a horizontal tube of swirling air. When that tube tilts down toward the ground, a funnel cloud is formed.
Funnel clouds can be nearly invisible but as they touch the ground, a tornado is formed. The tornado stirs up dust and debris – it is the dirt inside the tornado that makes it the angry dark colour we’re so used to seeing in pictures or videos. The flying debris is the most dangerous part of a tornado to people.
Tornados form on every continent in the world except for Antarctica, but the most common place for them is in the United States. The warm winds from the Gulf of Mexico meet the cold winds from the Rocky Mountains over an area of the United States referred to as “Tornado Alley” which encompasses the states of Kansas, Oklahoma and Texas. This is where we find the most tornados in the world.
Tornados are classified using the Fujita Scale – between F0 and F5 based on the damage they cause. F0 tornados aren’t very dangerous – they just stir up dust and break a few tree limbs. F5 tornados are potentially deadly, destroying houses, lifting cars and causing damage to towns and cities that can take years to repair.