How Come? by Kathy Wollard

Author:Kathy Wollard
Language: eng
Format: epub
Publisher: Workman Publishing Company

How do clouds get electricity to make lightning?

Electricity is something we think is made in power plants, not in puffy masses of water droplets that you can put your hand right through. But there is electricity in clouds, and in this page, and even in you.

Everything is made of atoms, from clouds to trees to human beings. Each atom has a nucleus made up of positively charged protons and neutral neutrons. (Except for the simplest kind of hydrogen atom, which has one proton and no neutrons.) Orbiting the nucleus are negatively charged electrons. Positives and negatives attract, so the electrons circle the nucleus like bees swarming around a sweet roll.

The attraction between protons and electrons is caused by the electromagnetic force. So electricity is already present everywhere we look. It’s just hidden inside atoms.

Ordinarily, the positive and negative charges balance each other out in each atom. So objects made of atoms—such as you—don’t usually have a positive or negative electric charge. And you don’t ordinarily go around zapping other people each time you touch them.

Sometimes, the electric charges in an object can become unbalanced. You’ve probably experienced this, perhaps on a cold winter day, in your toasty-warm home. Let’s say the rooms are very dry. You go scuffing across the carpet. And, unbeknownst to you, some electrons in the rug and in your shoes get sheared away from their atoms.

Now you are electrically charged. The number of electrons and protons in you don’t balance out. Touch a metal doorknob, and a tiny electric current will flow between you and it. You’ll feel the shock. If it’s dark, you can even see a spark. (The bright flash occurs because the electrons emit photons of light as they jump.) If it’s quiet, you might hear a tiny crackle.

Electricity is always in and around us, and clouds are no exception. They look harmless enough on a bright sunny day. But just like you in your living room, a cloud can build up a charge. If it does, watch out. When a cloud puts its atoms back in balance, there are fireworks.

What happens is this: In dark, towering storm clouds, there are rushing air currents that cause particles in the cloud—including salt from the ocean, dust, soil, and soot—to slam into each other. The colliding particles loosen electrons. The particles then become electrically charged—positively charged if they lose electrons, negatively charged if they gain too many.

For reasons that aren’t entirely known, heavier particles tend to get negatively charged, and lighter particles become positive. So the lower layers of the cloud, where the heavier particles fall, become negatively charged.

The negative bottom of the cloud attracts positively charged protons and repels any stray electrons on the Earth below. Soon, a positive charge builds up on the ground beneath the cloud. Then, just as electrons jumped between you and the doorknob, a tremendous spark—a lightning bolt—connects the cloud and the ground. Electrons zigzag down, meeting protons on their way up from the ground. And instead of a tiny crackle, a clap of thunder erupts.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.