What is the cause of thunder?

Question

How does it happen?

Answer 1

Sudden heating of air by the electric arc causes it to expand quickly, rather like an explosion.

Answer 2

Thunder is nothing but the noise of the lightning discharge.Heat from a lightning flash  which can reach 30000 degree celsius causes the surrounding air molecules to expand rapidly(faster than the speed of sound) producing the sound waves we hear as thunder.Because light travels faster than sound,we see lightning before hearing the thunder.

Answer 3

Lightning is incredibly hot. The heat of the lightning is transferred to the surrounding air. When air (or any gas) is heated it expands. When air expands it causes a pressure wave (try heating a partially filled balloon with warm water, it'll expand due to the increased pressure of the warmed up air). All sound is is a pressure wave. So what you're hearing is the pressure created from the rapidly heated air.  

Answer 4

  It is caused by the expansion of super heated gases that are the result of lightning strikes.

Answer 5

Here's how it works...

"As lightning connects to the ground from the clouds, a second stroke of lightning will return from the ground to the clouds, following the same channel as the first strike. The heat from the electricity of this return stroke raises the temperature of the surrounding air to around 27,000 C° (48,632 F°). Since the lightning takes so little time to go from point A to point B, the heated air has no time to expand. The heated air is compressed, raising the air from 10 to 100 times the normal atmospheric pressure. The compressed air explodes outward from the channel, forming a shock wave of compressed particles in every direction. Like an explosion, the rapidly expanding waves of compressed air create a loud, booming burst of noise."

You don't have to see the lighting to hear the thunder.

The lighting can be in the clouds behind the trees or over the horizon.

Answer 6

bolt of lighting breaking the sound barrier