What is the sound in the thunderstorm scene?

The sky suddenly cracked, and raindrops the size of beans poured out from it. First it was a mess, and then it poured down evenly. Soon, the ground became a stream. The wind, mixed with thunder, grew louder and louder. Lightning flashed across the road from time to time. With the thunder, the raindrops became more and more violent, like dense bullets on the battlefield, making a thunderous sound.