Thunder makes noise because it is the sound produced by the rapid expansion and contraction of the air surrounding a lightning bolt. When lightning strikes, it heats the air around it extremely quickly to temperatures as high as about 27,000°C (48,632°F). This sudden heating causes the air to expand explosively, creating a shock wave similar to a sonic boom. As the heated air expands, it compresses the surrounding air, and then as it cools, it contracts. This rapid expansion and contraction of air pressure sends sound waves that we hear as thunder. The loud booming sound occurs due to the shock wave created by this explosive expansion of air along the lightning bolt’s path. The length, rumbling quality, and variations in thunder sounds can be affected by the shape of the lightning bolt (e.g., forked lightning), distance, echoes from clouds and terrain, and atmospheric conditions. The initial sharp sound is from the closest part of the lightning, followed by a rumbling as sounds from other parts reach the listener later.
