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.

With nearby lightning strikes the thunder will sound like a loud bang, crack or snap and its duration will be very short. As the shock wave propagates away from the strike center, it stretches, diminishes, and becomes elongated. Then other shock waves from more distance locations arrive at the listener.

Thunder is the sound caused by lightning. Depending upon the distance from and nature of the lightning, it can range from a long, low rumble to a sudden, loud crack. The sudden increase in temperature and hence pressure caused by the lightning produces rapid expansion of the air in the path of a lightning bolt.

Thunder is the acoustic shock wave resulting from the extreme heat generated by a lightning flash. It is produced the same way regardless of whether lightning is positive or negative. Lightning can be as hot as 54,000°F (30,000°C), a temperature that is five times hotter than the surface of the Sun!