What does rolling thunder indicate?

Question

I've recently heard thunder that keeps on booming for 10 or more seconds... what does this indicate? Can anyone explain why this happens?

Answer 1

It likely means that the strike was rather far away, thus allowing the sound wave to echo and reverberate off of many objects, which in turn causes the sound to be stretched out and more rolling in nature.

Answer 2

One explanation I've learned is that the lightning is from cloud to cloud. If the lightning moves laterally at 2km up in the air all of the sound created by it will take about the same amount of time to reach your ears, thus a prolonged thunderclap. As opposed to cloud-to-ground where the lightining comes closer to you simply because its on the ground. There's a whole thing explaining it through triangles and whatnot but I'll spare you all. It's pretty much cuz the thunder ALL has to travel 2km down to you at a constant rate instead of coming closer to you so you can hear it sooner.

Answer 3

A prolonged thunder indicates multiple lightning strikes. Lightning is known to have multiple strikes in one spot, therefore causing multiple waves of thunder.

EDIT: cyswxman has a good answer as well. That is another possibility.