The temperature of the air in the lightning channel may reach as high as 50,000 degrees Fahrenheit, 5 times hotter than the surface of the sun. Immediately after the flash, the air cools and contracts quickly. This rapid expansion and contraction creates the sound wave that we hear as thunder.

: the sound that follows a flash of lightning and is caused by sudden expansion of the air in the path of the electrical discharge. 2. : bang, rumble. the thunder of big guns.

The initial sound reaches the ear with a loud bang, crack, or snap. As shock waves propagate away from the path of the lightning bolt, they are distorted, becoming stretched and elongated. The sound is more muted. Other shock waves from more distant locations arrive at the listener.

When the attraction becomes too strong, the positive and negative charges come together, or discharge, to balance the difference in a flash of lightning (sometimes known as a lightning strike or lightning bolt). The rapid expansion and heating of air caused by lightning produces the accompanying loud clap of thunder.