When a storm cloud discharges electricity to Earth, a small "leader stroke" zigzags toward the ground in about one one-hundredth of a second. Once it touches something-a tree, a pole, a barn or the ground- the electrical circuit is complete and a vast surge of electricity, the lightning bolt, roars up the path established by the leader stroke. Thus the lightning stroke generally goes from the highest object on the ground up to the cloud. It looks as if it happens the other way around-from the cloud to the ground. The human eye cannot follow the formation of a lightning stroke because it shoots skyward in about one-millionth of a second. What the eye sees is the electrical discharge of as much as 100 million volts of electricity, which heats the surrounding air to a temperature five times hotter than the surface of the sun - 30 000 degrees C (54,000°F). A lightning bolt is just a few centimetres wide. Thunder is the sound caused by the instantaneous heating and expansion of air along the lightning bolt. The variety of thunder sounds is caused by the different shape of each bolt.

You see the lightning first and hear the thunder later because light travels about a million times faster than sound. A lightning flash is seen from a distance as soon as it occurs, but the thunder from the same flash takes a few seconds to reach the observer. By counting the number of seconds between the flash and the thunder and dividing by three, you can calculate the lightning's distance from you in kilometres (divide by five for miles). For example if you count 6 seconds from the moment of the lightning flash to the sound of thunder, the distance to the lightning is 2.0 km
(6 divided by 3 = 2).

During a powerful lightning flash such as the one in this time-exposure photograph, objects hit include houses, trees, light standards, vehicles, lakes, or swimming pools. Houses and cars are generally safe places for people to be during a thunderstorm. Water, open fields and solitary trees are not.

SO - lightning DOES strike from the ground up - - WOW!!

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