The sound of thunder is caused by the rapid expansion of air surrounding the path of a lightning bolt. When lightning occurs, it heats the air around it to extremely high temperatures (around 27,000°C or 48,632°F), which causes the air to expand explosively and create a shock wave. This shock wave manifests as the loud booming sound we call thunder. The initial rapid expansion compresses the surrounding air, and as the air cools and contracts, the thunder sound continues as a rumble or series of grumbles, depending on the lightning's shape and path. The shock wave travels outward in every direction from the lightning channel, producing thunder that can range from a sharp crack to a prolonged rumble.
