Thunder

Thunder is the loud rumbling or booming sound you hear during a storm. It always comes with lightning. Sometimes thunder sounds like a sharp crack, and sometimes it rolls for a long time. Thunder is made by the lightning itself.

How Thunder Is Made

When lightning flashes, it heats the air around it very fast. The hot air grows bigger very quickly. This makes a big wave of sound, which is the thunder. The longer the lightning bolt, the louder the thunder can be.

Why You See Lightning First

You always see lightning before you hear thunder. This is because light travels much faster than sound. You can count the seconds between the flash and the boom. Every five seconds means the storm is about one mile away.

Fun Facts

• Thunder cannot happen without lightning.
• The sound of thunder can travel over 10 miles.
• A fear of thunder is called astraphobia.

Did You Know?

Long ago, people thought thunder was the sound of gods fighting or hammering in the sky.