'Thunder is caused by the rapid expansion of the air surrounding the path of a lightning bolt.

From the clouds to a nearby tree or roof, a lightning bolt takes only a few thousandths of a second to split through the air. The loud thunder that follows the lightning bolt is commonly said to come from the bolt itself. However, the grumbles and growls we hear in thunderstorms actually come from the rapid expansion of the air surrounding the lightning bolt.

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.'

Thunder is the sound caused by lightning. Depending on the distance and nature of the lightning, thunder can range from a sharp, loud crack to a long, low rumble (brontide). The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within a bolt of lightning.

From the clouds to a nearby tree or roof, a lightning bolt takes only a few thousandths of a second to split through the air. The loud thunder that follows the lightning bolt is commonly said to come from the bolt itself. However, the grumbles and growls we hear in thunderstorms actually come from the rapid expansion of the air surrounding the lightning bolt.

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.

Lightning heats up the air really really hot, which forces the air to expand and spread out, and between the lightning and you it's like a really long line at a fun ride where the last person in line pushes the person in front of them, who then pushes the next person, and so on, and you're in the front of the line and eventually you get pushed. But with thunder, instead of feeling being pushed, you hear the air that's been pushed, and it sounds like thunder.

From the clouds to a nearby tree or roof, a lightning bolt takes only a few thousandths of a second to split through the air. The loud thunder that follows the lightning bolt is commonly said to come from the bolt itself. However, the grumbles and growls we hear in thunderstorms actually come from the rapid expansion of the air surrounding the lightning bolt.

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.