Thunder is the sound that we hear after lightning during a thunderstorm. Sounds simple enough, but why does lightning even make a sound?
Any sound you hear is made up of vibrations. The vibrations travel as a sound wave through the air, until they reach your ear. Lightning is a huge discharge of electricity, and this electricity shoots through the air, causing vibrations to be formed in two ways:
1. The electricity passes through the air and causes air particles to vibrate. The vibrations are heard as sound.
2. The lightning is also very hot and heats up the air around it. Hot air expands, and in this case the air expands very quickly, pushing apart the air particles with force and creating more vibrations.
This is what we hear and call thunder – the rumbling of thunder is simply caused by the vibration or sound of the air affected by lightning. Most of the time we hear thunder as a loud, long rumble.
The more common rumbling effect happens when thunder echoes off objects all around us. This happens a lot in towns and cities, where there are lots of buildings for the noise to bounce off.
Why is thunder not at the same time as the lightning?
We see the lightning before we hear the thunder because light travels faster than sound. The light from the lightning travels to our eyes much quicker than the sound from the lightning. so we hear it later than we see it.