Air is everywhere about you. Every crack, hole, and space that is not already filled with something else is filled with air. Every time you breathe, your lungs are filled with air. Even though you cannot see air, nor taste it, nor feel it (unless the wind is blowing), the air is a “something”. It is a substance or material which scientists call “matter”. The matter may be a solid, a liquid, or a gas. The matter called “air” is almost always a gas.
In fact, the air is made up of certain gases. Two of these, nitrogen and oxygen, make up 99 percent of the air. They are always found in the same proportion of about 78 percent nitrogen and about 21 percent oxygen. There is also a small amount of carbon dioxide in the air which is added to it by living things. The remaining part of 1 percent is made up of what are called rare gases: argon, neon, helium, krypton. and xenon.
The great ocean of air extends for many miles above the surface of the earth. Because air is something, gravity attracts, or holds it, to the earth. Thus air has weight. The weight of the air exerts pressure. The air presses on your whole body from all directions, just as water would if you were at the bottom of the sea.
If you climb a high mountain or go up in an airplane, there is less air above you, so the pressure is less as you go up. About eight miles up, the pressure is only one-eighth of that at sea level. At 62 miles, there is almost no pressure.
What Is Air Made Of?
Air is mostly gas. The air in Earth’s atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen. Air also has small amounts of lots of other gases, too, such as carbon dioxide, neon, and hydrogen.