Weather and Meteorology - Glossary
Included in this glossary you'll find terms related to our public forecasting program, weather observations and unique terminology that is of Environment Canada's hurricane centre and ice service products.
Tornadoes are referred to as funnel clouds until they touch the ground. They are spawned by severe thunderstorms, and are violent, funnel-shaped wind vortexes in the lower atmosphere, with upward spiralling winds of high speeds.
The tornado usually appears from a bulge in the base of a cumulonimbus cloud. It can be tens to hundreds of metres wide and have a lifespan of minutes or hours. In terms of size and area, it is one of the least extensive of all storms, but in terms of how violent storms can be, it is the world's most severe.
More tornadoes occur in the United States than in any other country. In Canada, tornadoes occur mostly on the Prairies and in Southern Ontario.
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