Canadian Geographic
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INSIDE: Anatomy of a thunderstorm Go now!

Thunderstorms begin when a parcel of warm, moist air begins to rise.


Anatomy of a thunderstorm

A combination of the sun’s heat and the earth’s rotation powers the movement of winds carrying weather systems across the globe — and across the length and breadth of Canada. The temperature differences between the poles and the equator provide the energy that drives atmospheric circulation: low-pressure polar air sinks and migrates to the equator while high-pressure warm air from the tropics rises and moves to the poles. This global circulation system is the mechanism that drives Canada’s daily weather. In low-pressure areas, warm air rises and cools, forming clouds, which bring rain, fog, snow, hail, and thunderstorms. In high-pressure areas, cold air descends and, as it falls, it is compressed and heats up, generally bringing clear, warm, and settled weather. Canada’s vast size and varied landscape also influence day-to-day conditions, some of which include the record-breaking weather extremes described in this section.



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Climate zones


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Quiz :

Where does the Atlantic maritime tropical air mass come from?

The Pacific coast
The Arctic Ocean
The Gulf of Mexico