Where does the energy in lightning come from?

(Lansing State Journal, June 25, 1997)

Question submitted by Scott O'Connell

In order to understand this first, we need to understand the nature of atoms. Atoms are the basic building blocks of matter. Each atom has a nucleus that is made up of positively charged protons and uncharged neutrons. Since positive and negative particles attract, negatively charged electrons orbit the nucleus. This attraction is caused by a force called the electromagnetic force.

In storm clouds, there are air currents that cause particles in the cloud such as dust and salt from the ocean to collide with each other. Sometimes these collisions result in the liberation of electrons. If a particle gains an electron, then it becomes negatively charged and if a particle loses an electron it becomes positively charged. Heavier particles tend to gain electrons while lighter ones tend to lose them. Since the heavier particles occupy the lower layers of the cloud, these layers become negatively charged. As the bottom of the cloud becomes negatively charged, it begins to attract positively charged particles and repel stray electrons from the Earth. Thus, a positive charged builds up on the ground beneath the cloud.

As a result a lightning bolt connects the cloud and the ground. Electrons from the cloud travel toward the Earth and encounter positively charged particles travelling toward the cloud from the Earth. When these particles encounter each other, a clap of thunder is heard. If we could slow this process down we would see that there are actually many bolts of lightning snaking between the cloud and the Earth, but they happen so quickly that we only see one lightning bolt.

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