Lightning is an electric current, and just like the electricity lurking in the outlets in your house, it can be deadly. Have you ever gotten a shock by shuffling across a carpet and then touching something made of metal? Then you've experienced the same process that makes lightning.
Within a thundercloud, many small bits of ice bump into each other as they swirl around in the air. All those collisions create an electrical charge, just like the one that built up in you when you crossed the carpet.
After a while, the whole cloud fills up with electrical charges (usually with a negative charge closest to the earth). Since opposites attract each other, that causes a positive charge to build up on the ground beneath the cloud.
The ground's electrical charge concentrates around anything that sticks up, such as mountains, lone trees, people, or even blades of grass. The charge streaming up from these points eventually connects with a charge reaching down from the clouds, and--zap!--lightning strikes.
The intense heat of the lightning bolt causes the surrounding air to explode outward with a gigantic boom--thunder.
- A lightning flash is no more than one inch wide.
- The temperature of a lightning flash is 15,000 to 60,000 degrees Fahrenheit. That's hotter than the surface of the sun (9,000 degrees Fahrenheit).
- A stroke of lightning moves about 62,000 miles per second--one-third the speed of light.
- A single lightning flash carries an electric current as high as 300,000 amperes. For comparison, electrical wiring in a house carries 20 or 30 amperes.
- What we see as a flash of lightning may actually be three or four different strokes in exactly the same place, one right after another. That's why lightning seems to flicker.
- Power failures caused by lightning strikes cost utility companies as much as $1 billion annually.
- The Guinness Book of World Records lists Roy Sullivan of Virginia as the human being struck by lightning the most times: seven. This is one record you don't want to beat!