What causes the booming sound of thunder?

The booming sound of thunder is caused by the rapid expansion and contraction of air surrounding a lightning bolt. When lightning strikes, it heats the air to temperatures as high as 30,000 degrees Fahrenheit in a fraction of a second, causing the air to expand explosively. This rapid expansion creates shock waves that we hear as thunder. The sound can vary in intensity and duration depending on factors like the distance of the lightning strike and atmospheric conditions.