Air - The Atmosphere

When you get chilly, you might wrap up in a nice warm blanket. The Earth has a blanket too, called the atmosphere. We usually call it air for short. The blanket of air that surrounds the Earth keeps us comfortable. We wouldn't be able to live on Earth without an atmosphere.

Earth isn't the only planet with an atmosphere. Some planets have an atmosphere made up of toxic chemicals. Some big planets, like Jupiter, are all atmosphere. Earth, however, is the only planet that we know of, so far, that has an atmosphere that makes life possible.

Earth's atmosphere is made up of many different chemicals, most of them in very small amounts. The main chemicals in air are oxygen at 21%, nitrogen at 78%, and argon at less than 1%. Some other chemicals that are there in very small amounts are important too. There are carbon dioxide, water vapor, ozone, and man-made gases, including chlorofluorocarbons (CFCs).