The atmosphere is all the air surrounding the earth. Without it, we would be forced to see

k shelter from the sun, as there would be no atmosphere to protect us from the sun's deadly rays.

Large and powerful, the atmosphere consists of an ocean of gases hundreds of miles high. It presses down on our bodies with a force of more than fourteen pounds per square inch. The narrow column of air which rests upon our shoulders weighs almost 2000 pounds. But our bodies are built in such a way that this weight does not crush (压碎) us.

In this huge ocean of air there is more energy than in all the coal, oil, and gas we have on earth. Electrical energy is collected in the atmosphere as water is collected and stored in a dam. The existence of electricity in the air has been known for centuries. But a thorough study of electricity in the atmosphere was not possible until the development of radio and radar.

One scientist, Dr. Sydney Chapman, has tried to explain the electric field which surrounds the earth. He believes that great storms on the sun create large amounts of electric energy. This energy is contained in a very light gas called hydrogen. The earth pulls the gas toward it, and a ring is formed around the earth several thousand feet above its surface. The great space ring is a powerful current of electrical energy. Sometimes the ring comes down and curves into the lower atmosphere, causing strange electrical effects.

His idea explains many things. It has long been known that there is an electric field inside the earth. It moves in much the same manner as the electric energy contained in the atmosphere. Scientists now believe that the electric energy in the atmosphere causes the electric energy inside the earth to flow.

If we can learn to control the energy in the atmosphere, we will have an unending supply of energy. Many scientists are trying to learn how to control it, In the meantime, even those of us who are not scientists have begun to pay attention to air. We realize that air does not contain the same elements that it contained years age. Automobiles, airplanes, factories, and atomic explosions have added dust and waste gases to the atmosphere. It is time to learn how to protect our atmosphere, the roof over the world of man.

We know the atmosphere as ______.

A．the total amount of oxygen over the earth

B．mixture of gases surrounding the earth

C．a source of storms

D．the diffusion of waste gas