why does it thunder

Thunder is caused by the rapid expansion and contraction of air surrounding a lightning bolt. When lightning strikes, it heats the air around it to extremely high temperatures—up to about 27,000 to 30,000 degrees Celsius—which causes the air to expand explosively. This rapid expansion creates a shock wave that produces the loud booming sound known as thunder. As the air cools and contracts afterward, it generates the rumbling or rolling sounds often heard following the initial thunderclap. The sound varies depending on the distance and nature of the lightning bolt, sometimes being a sharp crack or a long rumble due to echoes and interactions of shock waves from different parts of the bolt.