What Causes the ‘Sound’ of a Thunderclap and How Is It Different from Lightning?

Thunder is the sound of lightning. When lightning strikes, it creates a big flash and also makes a loud boom. The boom happens because lightning heats up the air really fast, making it expand like a balloon popping. That expansion pushes the air around it, creating waves we hear as thunder. Light travels faster than sound, so you see the lightning before you hear the thunder.

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Examples

When you hear thunder right after seeing a flash of lightning, it's because the sound takes time to reach your ears.
Thunder sounds like a boom when lightning is close, but it rumbles if it’s far away.
You can sometimes see lightning and hear two different booms, one from the main strike, another from the return stroke.

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Categories: Physics · sound,lightning,waves,acoustics