Thunderstorms usually erupt at the end of a hot summer day when cumulonimbus clouds are fully developed. Giant cumulonimbus thunderheads can measure more than 20 kilometres (12 miles) from top to bottom. Vertical air currents carrying moisture, water droplets and ice crystals within the huge clouds can create positive and negative electrical charges in the cloud. The electrical charges are released by lightning flashing either within the cloud or between the cloud and the ground. And, yes, lightning can occur during a snowstorm in winter and can strike in the same place more than once.

Lightning looks as if it has enormous power - and it DOES. Because there is always a thunderstorm somewhere, ABOUT 100 LIGHTNING BOLTS STRIKE the EARTH EVERY SECOND. Scientists estimate that this yields a continuous power output of four billion kilowatts - enough to supply all of Canada's energy needs.

When lightning hits a tree, the moisture in the wood instantly expands and turns to steam, causing the tree to explode and send pieces flying in all directions. Even though some bolts are forked, usually only one prong actually completes the discharge.

Sometimes during a thunderstorm, only sudden glows in the clouds are seen, rather than lightning bolts. This is often called heat or SHEET lightning. It is not a special type of lightning. Instead, the lightning is simply blocked from view by the clouds so a pulse of light is seen but the bolt itself is hidden.

Does lightning strike from the GROUND UP? - - Uhh?? -->

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