The Science Behind Thunder

Thunder starts with lightning. That giant spark of electricity in the sky. The buildup of electrical energy in storm clouds can’t stay in one place for long, so it looks for a way out. Sometimes, it travels from cloud to cloud, other times, it moves to the ground.

I’m sure you already know; lightning is fast and extraordinarily powerful. The iconic flash of light only lasts a fraction of a second, but the energy it holds is the key to how thunder is created.

When lightning flashes, it heats the surrounding air to temperatures reaching up to 30,000 Kelvin, (about 29,726 degrees Celsius or 53,540 degrees Fahrenheit). This heat causes the air to expand. Rapidly. Imagine blowing up a balloon, the air inside pushes outward, causing the balloon to stretch and grow. The air surrounding lightning reacts the same, it expands like a balloon. Just on a much larger scale. The expansion happens so fast that it creates a shockwave in the air.

The shockwave from the lightning’s heat creates sound waves, which we hear as thunder. When air expands and then contracts rapidly, it produces vibrations. These vibrations travel through the air, carrying the sound of thunder to your ears. Think of it like clapping your hands. When your hands hit each other, they push the air and create a sound. With thunder, the clap is just louder.

Not all thunder sounds the same. Sometimes it’s a sharp, whip-like crack. Sometimes it’s a long, rumbling noise. The type of sound depends on where the lightning is created and how the sound waves travel to your ears. If the lightning is close, the sound reaches you almost all at once. If the lightning is farther away, the sound waves bounce off building, hills, and even clouds before reaching you. Creating the rumbling echo that can last several seconds.

Thunder is the sound of lightning’s power. By learning how thunder is created, we can appreciate the incredible natural forces at work on our planet.