Lightning and Thunder

Lightning is a bright flash of light during a thunderstorm. Some bolts of lightning travel from cloud to cloud. Some bolts of lightning travel from a cloud down to the ground. Lightning usually strikes high points in the landscape - like mountaintops or tall trees. A bolt of lightning is so hot that it causes the air along its path to expand, which creates the rumble of thunder. 

Lightning striking a mountaintop

Lightning usually strikes high points in the landscape - like this mountaintop.

NPS/Yellowstone National Park/Neal Herbert

Why Does Lightning Happen?

Have you ever shuffled your feet across a carpet wearing socks and then felt a little zap when you touched something? 

When you shuttle across the carpet, you are making a little static electricity. Electricity forms when charged particles collect together and flow towards particles with the opposite charge.

Tiny particles with a negative charge rub off the carpet and onto your feet. When you touch something, they race toward particles with a positive charge while the positively charged particles race towards the negative charge. That’s what makes the zap. Static electricity is like a tiny bolt of lightning. 

The same thing happens in a thunderstorm. The graphics below describe how lightning forms. 

Graphic showing how lightning forms. As air moves around in a cumlonimbus cloud, some negative charges rub off. They collect in the cloud. Positive charges near the ground are attracted to the negative charges in the cloud.  They climb to the highest point to get near the negative charges. The amount of charged particles grows and grows. When large enough, the negative charges flow down, and the positive charges flow up, making a bolt of lightning.

UCAR/L.S. Gardiner