eli5: How is sound produced in the clouds during thunderstorms?
In: Physics
Lightning creates a huge, fast vacuum as soon as the lightning dissipates, when the air around it fills in that space, it creates the thunderclap, which you hear.
So you know hot gases expand and cool gases contract, right? With a literal kid you could put a balloon in the freezer and out in the sun and compare what happens to its size as the temperature changes. That’s how gases work – hot gases get bigger.
Ok now think about what lightning is. A bolt of lightning can reach 50,000 F, 5x hotter than the surface of the sun!! The air around the bolt gets very hot very fast. That makes it expand very much, very fast. And then slam back down to normal size as it expands into normal temp air and cools down.
The final piece is what sound is – it’s pressure waves in air. When the air pressure quickly goes up and down, your ears detect that as a noise. With a literal child, sound is wiggles in the air that wiggle your ear when you hear them.
See how that all connects? The lightning heats the air. It expands super fast and bangs into the surrounding air. Which bangs into the air next to it, which bangs into the air next to it…until it bangs into your ear with all that energy. Boom!
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