Why is some thunder a sudden loud bang (with minor echos), while other times it’s a long drawn-out roll that goes on & on? Is it simply how close I am to the lightning, or is there more to it?
In: Physics
This is multipath interference.
If you are close to the lightning, you hear a sharp clap, because there aren’t many ways to cover a short distance. You hear echos when the shortest path to you is supplemented with a reflection from some distant reflector (building, canyon, …).
If you are farther from the lightning, the shortest path is still the first sound you hear, but lots of shallow reflections of buildings that are mostly “on the way” from the lightning to you are only slightly delayed. Sometimes this causes interference, particularly the higher the frequency. The remaining low frequencies give the long low rumble.
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