Sunday, July 15, 2007

What Causes Lightning And Thunder?

This summer we have already seen several thunderstorms that came upon us suddenly during the day. Along with the sudden rains they also bring with them some grand displays of nature's firepower - lightning and thunder. Have you ever wondered what lightning is all about and why lightning and thunder always come together, or well, almost together? Today, we will learn about all of these.

Lightning is basically the flow of electrons, which are a fundamental form of matter. Lightning is in fact, very similar to the spark that you might see if you shuffle your feet and walk across the carpet and then touch a door knob? (Do not do it on purpose though!) Electrons are amongst the tiniest particles making up matter along with something called protons. Each atom (the fundamental building block of matter) has equal number of electrons and protons that balance each other.

When we shuffle our feet on the carpet, we pick up several electrons from the carpet. The small spark between your hand and the door was the transfer of electrons from your body to the door. This is because it is very hard to hold on to extra electrons, as they like to flow away immediately to maintain balance in matter.

Uneven heating of air causes a thunderstorm. A body of warm air is forced to rise by an approaching cold front therefore thunderstorm's form. In the case of lightning, the clouds up in the atmosphere contain several tiny ice crystals that rub together to produce charges. When these clouds come closer to earth, the electrons from earth jump up to the clouds and this causes a huge spark - that is, lightning. The flow of lightning in air is so fast that it pushes back some air and creates a channel in air. When the lightning has gone through, the air collapses back causing a loud rumbling sound - thunder. So thunder moves at the speed of sound, which is much slower that the speed of lightning which is almost as fast as light. You can read about a lot more experiments to do about lightning at Weather Wiz Kids.

Little Lion Experiment:

A very simple experiment to do involves the creation of charges and static electricity. Be careful and do this with adult supervision.

Items Needed:

  • A wooden or plastic ruler
  • Very small bits of paper, about half the size of your nail or much smaller than a penny
  • A plastic plate
  • A metal plate


  1. Spread out the bits of paper on the plastic plate and on a metal plate, keeping both plates on the floor.
  2. Rub the ruler against the your head (that is, hair) or on a carpet a few times.
  3. Now take the ruler close to the paper bits on the plastic plate. What happens?
  4. Rub the ruler again on the carpet and take it near bits on the metal plate. What happens now?