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How does thunder work?
Quick answer
Thunder works as the sound of lightning: a bolt heats the air around it so fast that the air explosively expands, creating a shockwave we hear as a boom. Because light travels faster than sound, you see the flash before you hear the thunder.
Step by step
- Lightning superheats the air to tens of thousands of degrees in an instant.
- The air expands explosively, creating a shockwave.
- That shockwave becomes the sound of thunder.
- Light reaches you almost instantly; sound takes about 3 seconds per kilometer.
- Counting the gap tells you roughly how far the lightning struck.
People also ask
What causes thunder?
A lightning bolt heats the surrounding air so suddenly that it expands explosively, producing a shockwave we hear as thunder.
Why do you see lightning before hearing thunder?
Light travels nearly a million times faster than sound, so the flash reaches you almost instantly while the boom lags behind.
How can you tell how far away lightning is?
Count the seconds between the flash and the thunder; sound travels about a kilometer every three seconds (a mile every five).
Part of the guide: Water & Weather Phenomena →