What is a thunderstorm? A thunderstorm is a weather pattern that includes thunder, lightning, and usually rain or hail. It can lead to tornadoes.   The basic need for thunderstorms is warm, moist air, so they happen most often in the tropical areas. Over land, thunderstorms strike more often in the afternoon and early evening since the ground heats up from the sun during the day. They occur more frequently on hot summer days than in cold weather.

Causes of Thunderstorms

• Moist air, heated by the sun, rises which causes an updraft of air.
• As warm air rises, water in the air forms clouds.
• When water vapor in the cloud gets too heavy, it falls as rain.
• Conflict between the warm updraft of air and cool water in the clouds causes thunder and lightning.
• The severity of the thunderstorm depends on the difference in temperature.

What causes lightning?	What causes thunder?
In a cloud, swift air separates water droplets, causing electrical charges. The electrical charges build up and causes huge electric shocks. It generates about 100 million volts of electricity.	Lightning causes thunder. When lightning strikes, it superheats the air around it. This causes a shockwave, kind of like throwing a rock into water. The ripples cause sound as they travel through the air.
Types of Lightning	Types of Thunderstorms
Heat - Lightning from storms that are so far away that we can't hear the thunder or see any rain. Sheet - Lightning that covers a wide area, and can be inside or between clouds. Forked - Bolts that most commonly occur between clouds and the earth. Ball - A very rare type. It is a sphere shape that glows and moves slowly. It appears to come from a storm cloud, and can last five seconds.	Single cell - A single, isolated thunderstorm Multi-cell, Cluster, or Line - A line of thunderstorms that feed and contribute to each other. Supercell - A very dangerous storm that can lead to tornadoes

Safety Tips
DO	DON'T
If you're outside, go into a house, large building, or car. If you must stay outside, stay away from... trees metal pipes, wire clotheslines and fences any body of water tractors and all farm equipment railroad tracks open areas Find a ditch or bridge and take shelter	Don't use the telephone (except emergencies) Don't go into any small buildings Don't go under any large trees Don't be taller than your surroundings Don't stand on a hilltop Don't go out in a boat Don't carry anything made of metal Don't be near large metal objects

Interesting Facts about Thunderstorms

• Thunderstorms are local weather disturbances. They usually affect only a few square miles.
• A single thunderstorm usually lasts only 30 to 40 minutes.
• A dying thunderstorm can trigger another thunderstorm.
• Lightning strikes the earth about 100 times per second.
• The energy released by a thunderstorm is thought to be larger than the explosion of a atomic bomb.
• About 100 Americans are killed each year by lightning.
• The dark color of clouds in thunderstorms is caused by water accumulation.