What Are Important Properties Of The Air

The atmosphere. When you hear the word explore, perhaps you think of an expedition to some distant, unknown land. Perhaps you think of explorations in Africa or at the south pole. Explorations at or near home, however, are constantly being made by scientists. Among the most important of these are explorations of the atmosphere.

Until recent times little has been known about the nature of the atmosphere or about how deep it is. Even today it has been explored for only a few miles above the ground. Before the invention of balloons and airplanes the atmosphere was studied chiefly near the earth’s surface. By climbing mountains men learned something about what the air is like a few thousand feet above sea level. They learned that when they climbed high mountains, it was hard for them to get enough air for breathing.

Men have long known that the ocean of air has no surface such as the oceans of water have. Nobody yet knows exactly how deep the atmosphere is. However, by observing “shooting stars” (meteors) scientists estimate that the air is at least two hundred miles deep. They also believe that beyond the atmosphere there is only a vacuum. A vacuum is a space that is completely empty. It is a space that has nothing whatever in it.

How do you suppose that scientists have been able to learn what they know about the atmosphere? One method is by sending up small balloons to which self-recording instruments are attached. Some of these balloons have risen more than twenty miles above the ground. At that height they burst. The instruments which they carried floated down by means of a parachute.
Men have been able to go up several miles into the air. In 1862 two Englishmen, Coxwell and Glaisher, rose in an open balloon to a height of about seven miles. At that height Glaisher became unconscious. Coxwell’s hands were so badly frozen that he could not use them. Nevertheless he succeeded in opening the gas valve of the balloon with his teeth. Thus the balloon was caused to descend and carry Coxwell and his helpless companion to safety.

Recently, daring aviators’ have been able to ascend for a few miles into the stratosphere. This is the region of the atmosphere above rains, clouds, snow, and frost. The men were able to endure the terrible cold at such heights only by riding in an airtight cabin in an airplane or in an airtight metal ball suspended from a balloon. Scientific facts of great interest are being learned from such explorations of the stratosphere.