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Tuesday, November 15, 2011

Static in the Sky

If you get zapped by static electricity, you sometimes see a little spark. What's the biggest spark you have ever seen? Here's a hint - you often see it in the summer during a storm. That's right - lightning is a giant static electric spark. What causes lightning?

It's those positive and negative charges again. The water molecules in rain, ice or snow bump into one another and build up negative charges on the bottom surface of the clouds, just like you built up negative charges by rubbing a balloon on your head. This makes things on the ground positive, and eventually electricity will flow between the cloud and the ground, making a very impressive lightning bolt. It travels to the ground at 140,000 miles per hour (220,000 km per hour), and the air around the bolt becomes several times hotter than the surface of the sun, at 54,000oF (30,000oC). All this energy makes the air molecules vibrate so much that they make noise - thunder! Lightning is beautiful, but very dangerous. If you are outside when at lightning storm starts, you should immediately go indoors!

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