why does thunder sound long and with a long rumble when the lightning is far away and why is it a short hard bang if it is really close?


Is it because some soundwaves travel slower than others?

In: Physics

Because of diffusion through the air and deflection off of whatever surfaces exist, meaning the amplitude is smaller and smaller as you get further away, and the time interval for the energy to dissipate gets longer.

Echoes. A sound that intense is going to produce an intense echo, even if the surface it’s reflecting off absorbs a fair bit of the sound. The further away from the source, the more time there is for the reflected waves to reverb around off of other surfaces and to separate. Thus, long rumble vs short blast.

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.

If you’re right next to me in the pool and I splash the water, it will smack against you sharply. If you’re at the other end of the pool, it will just be some waves that slowly ripple by you.

Sound waves behave a lot like water waves. If they have room to spread out, they will. There’s also the effect of echoes bouncing off of the surroundings, like waves off the side of a pool.