THUNDERSTORMS
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| A picture of a regular cumulonimbus cloud (left) and an anvil cumulonimbus cloud (right). This is a special cumulonimbus cloud that is wide and flat at the top. | |
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| A man holding some hail. Can you see how big and harmful these objects could be if they fell out of the sky? |
| Here is an awesome video of lightning bolts during a thunderstorm. Double click the image above to play the video! |
A thunderstorm is a type of storm that has rain, thunder, lighting, and sometimes hail. Thunderstorms form from cumulonimbus clouds, which are large masses of water vapor that can be 5-10 miles high.
A thunderstorm occurs when warm air rises. This can happen almost anywhere is the world. Most thunderstroms occur in places that are warm and humid. Also, they usually happen during the late afternoon. Thunderstorms last as long as 30 minutes to an hour.
As warm air rises into the cloud, cool air and rain is pushed down to the ground. This causes some of the wind gusts that come with thunderstorms.
Lightning is caused when electrical charges build up in the clouds. These charges are from the ice and water in the clouds colliding with each other. When the charges get big enough, lighting strikes. The shock waves from the lightning become sound waves, and that is what we hear when there is thunder.
Have you ever wondered why we can SEE lightning, but cannot hear it right away? Or why we can HEAR thunder when there is no lightning in the sky?
This happens because light waves (that help us see) move faster than sound waves (which we hear). Even though lightning and thunder happen at the same time, the light waves reach us faster than the sound waves. Because of this, you can guess how far lightning is from you by measuring the time difference between SEEING the lightning and HEARING the thunder. If you hear the thunder right after you see the lightning, THE LIGHTNING IS CLOSE BY! If there is a big time difference, then lightning is pretty far away.
Thunderstorms can be dangerous. They can cause a lot of rain and flooding. Thunderstorms, if they are strong enough, can sometimes cause hurricanes or tornadoes to form.
Lightning is also very dangerous. The temperature of a lightning bolt can reach 50,000 degrees F. This is hotter than the SUN! Lightning can cause fires where it strikes, and also kill people.
Hail that falls during thunderstorms can be as big as a softball, and can damage the cars and windows that it falls on. Sometimes, the hail can kill animals that get hit by it.
Contact: ymaini@bu.edu
Site Last Updated: 11-05-05