Canadian Geographic
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Extremes of weather

Terrifiying twisters

All regions of Canada except the Arctic experience tornadoes, or twisters. Tornadoes occur from March to late October, peaking in early summer, with the most frequently affected areas being southern Ontario and the Prairie provinces. Forming in thunderstorms (Anatomy of a thunderstorm) rotated by high winds, a tornado occurs when a downward-spinning column of air inside the thunderstorm touches the ground, creating a funnel-shaped twister that can cut a path up to 1.6 kilometres wide and 3.2 to 8 kilometres long. Winds range from weak (65 km/h) to devastating (500 km/h). The 1912 Regina twister, Canada’s deadliest, took 28 lives and destroyed the downtown area. Almost as destructive, the 1987 Edmonton tornado killed 27 people, injured over 200, and caused an estimated $250 million in damage.


Terrifying twisters This slide show includes four images of tornado funnel clouds in different settings.


On the next page:

Horrifying hurricanes

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Quiz :

What was the deadliest hurricane in Canada?

Hazel in 1954
Ivan in 2004
Andrew in 1992