A thunderstorm develops in an unstable atmosphere when warm moist air near the earth's surface rises quickly and cools. The moisture condenses to form rain droplets and dark thunder clouds. These storms are often accompanied by hail, lightning, heavy rain, high winds, and tornadoes. Thunderstorms are usually over in an hour, although a series of thunderstorms can last for several hours.
Hail forms when updrafts in thunderclouds carry raindrops upwards into extremely cold areas and freeze layer upon layer until they are too heavy and fall to the ground. Hailstones vary in size from peas to grapefruits and fall at great speed. People have been seriously injured by hailstones.
THINGS TO DO IN CASE OF A HAIL STORM
During a thunderstorm the air is charged with electricity. Bolts of lightning hit the ground at about 40,000 km per second - so fast that the series of strikes hitting the ground appear as a single bolt.
THINGS TO DO IN A LIGHTNING STORM
Lightning in Canada - Government of Canada
A heavy rainfall can result in flooding. This is particularly true when the ground is still frozen or already saturated from previous storms. Floods may also result if a heavy rain coincides with spring thaw.
THINGS TO DO IN CASE OF A HEAVY RAIN STORM
Tornadoes are violent windstorms identified by their twisting funnel-shaped cloud. They are always produced by thunderstorms but not every thunderstorm produces a tornado. They travel between 20 and 90 km/h often moving from the southwest to the northeast. They are erratic and can change course suddenly. It is not a good idea to chase tornadoes.
THINGS TO DO IN CASE OF A TORNADO
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