Wednesday, October 6, 2010

What is a Thunderstorm?

     A thunderstorm is millions of droplets of water vapor in the atmosphere that produce lightning, rainfall, winds, hail, and thunder. Thunderstorms form when instability in the atmosphere cause cumulonimbus clouds to form. Towards the tops of the thunderstorm water droplets become supercooled and is a region know as the anvil. This is where the thunderstorm can’t go any higher because the stratosphere is stable. The cloud starts to spread out along the bottom of the stratosphere. Dust is sucked into the cloud when growing so the supercooled water droplets come in contact with it and turn into to ice.
     If enough ice particles collide and clump together, a small hailstone will form. Forced by gravity, the hailstone falls toward the earth. If the updrafts are strong enough, the hailstone will be sucked back to the top of the storm and get bigger. This process continues until the hailstone is too large and the updraft can’t support it anymore. This causes it to fall to the earth.
     Lightning occurs when the ice particles in the cloud rub each other and cause friction which in turn charges the water droplets. Once enough charge builds between the ice particles rubbing against each other and the ground, the stage is set for lightning. A single lightning can heat the air around it to 30,000 degrees Celsius. This intense heating occurs so rapidly that air density cannot respond. The rapid rise in air temperature is accompanied by an increase in air pressure that generates a shock wave. The shock wave goes outward and produces thunder. This explains why it’s called thunderstorm.

http://michael.bsch.au.com/whatisstorm.html

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