Re: What creates thunder? Is it air, lighting, or a combination?

Please put only one space between words, and try to follow the rules for capitalizing words: it will make your question much easier to read.

Thunder and lightning are both caused by an "electrical discharge". Have you ever played with static electricity on a dry day by rubbing your feet on the carpet, and then touching a metal object? A spark will jump from your finger to the object. At the same time you see the spark, you will hear a tiny "snap!" noise. This is an electrical discharge. Thunder and lightning are exactly the same thing -- they're caused by a much, MUCH bigger spark jumping from a thundercloud to the ground, or jumping between different parts of the cloud.

How does it happen? A spark jumps between two objects when one object has too many electrons, and the other has too few. (Electrons are the tiny particles which form the outer layers of atoms: when they move from one place to another, we call it "electrical current".) If one object has far too few electrons, it can steal them away from the atoms that make up the air. An object with far too many electrons will dump them onto the air atoms. The atoms in air pass electrons from one to the other, carrying electrons from the object that has too many toward the object that has too few, until everything becomes even.

BUT, every time an electron meets up with an air atom which wants one, a bit of energy is released. This energy takes the form of light and heat. There are so many atoms doing this at the same time that the light forms a single bright flash, and the heat causes the air to reach a temperature of thousands of degrees. The hot air expands like an explosion, producing a sound wave which we hear. It sounds like a little "snap!" for a small spark, or a giant "bang!" for a huge lightning bolt.

It's easy to see why lightning makes a giant "bang!" noise when we consider how much energy gets dumped into the air by the flow of electricity in a lightning bolt. According to this site, a lightning bolt has as much energy as the explosion of over 5 tons of dynamite!!!

The next big puzzle is, "how does the cloud get extra electrons in the first place?" But that's a question for another day.

The University of Michigan has a wonderful website about Earth and Space Science, which includes this page on lightning and thunder