A thunderstorm is coming. A bolt of lightning flashes across the sky. Thunder rumbles in the distance. The storm comes closer. The lightning bolts get brighter. They light up the clouds. The thunder gets louder. It crashes and roars. Thunder and lightning can be frightening.
WHAT IS LIGHTNING?
Lightning is a big electric spark. Sometimes the spark goes between a cloud and the ground. Sometimes the spark goes between two clouds.
Lightning is caused by a kind of electricity called static electricity. Did you ever feel a shock when you touched a metal doorknob? The shock came from static electricity. You can make static electricity if you scuff your feet across carpet and touch something metal.
Static electricity comes from tiny invisible electric charges. There are positive charges and negative charges. Too much positive or negative charge in different things makes static electricity.
Negative charges can build up in a storm cloud. Positive charges can build up in the ground or in another cloud. Negative and positive charges pull toward each other. Once enough of them build up, the charges jump toward one another. The jumping charges make a big electric spark. The big electric spark is lightning.
WHAT IS THUNDER?
Thunder sounds like an explosion. Lightning causes thunder. The sound comes from air that suddenly gets very hot.
A bolt of lightning can make the air around it as hot as 18,000° Fahrenheit (10,000° Celsius). That’s hotter than the surface of the Sun! The hot air rushes away from the lightning bolt. The air rushing away makes the loud sound of thunder.
You often hear the thunder after you see a bolt of lightning. This is because sound travels slower than light. The farther away the lightning is, the longer it takes for you to hear the thunder. You can tell how far away the lightning is. You can count the seconds between the lightning and the sound of the thunder it makes. Sound travels about 1 mile (about 1.6 kilometers) every 5 seconds. If you count slowly to 5 and hear thunder, the lightning bolt was about 1 mile away. If you count to 15 before you hear thunder, the lightning bolt was 3 miles away.
CAN THUNDER AND LIGHTNING HURT PEOPLE?
Thunder cannot hurt you. Lightning can hurt people. There are things you can do to stay safe during a thunderstorm.
Do not stand under a tree to stay out of the rain. Lightning often strikes trees. Do not stand close to a window or talk on a telephone. Lightning can make windows shatter and can travel through wires.
The best place to be during a thunderstorm is indoors. If you are outdoors, the safest place to be is inside a car.