Is it because some soundwaves travel slower than others?
In: Physics
Think about if you were standing right next to a lightning strike. Obviously you almost immediately hear the bang from the superheated air right next to you, but consider that the lightning bolt is likely a mile long; you are also going to hear the sound from the parts of the bolt above you as they arrive at the speed of sound.
Then that sound is going to expand out and hit other things, bouncing off them as well. That building nearby is going to reflect some sound back, as will the nearby hill, etc. The result is you are going to be hearing that lightning bolt for a while, and if you are a long way away the difference in travel time can become significant.
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