Thunder is the loud sound that follows a flash of lightning during a storm. It happens when the intense heat from the lightning bolt causes the air around it to expand rapidly. This sudden expansion creates shock waves that we hear as thunder. The sound can vary from a low rumble to a sharp crack, depending on how far away the lightning strike is. People often associate thunder with rain and storms, but it can also occur in dry conditions. Many cultures have myths and stories about thunder gods or spirits that explain this powerful natural phenomenon. Understanding thunder helps us appreciate the beauty and power of nature.