?  Library of Wonders The Wonder of  Air

What is air? What is the atmosphere?

Air is absolutely necessary for us to live. The Earth is surrounded by air. We call the air surrounding the Earth the atmosphere. The atmosphere is only around 10 kilometers thick. This is less than 1/1,000th of the Earth’s diameter. In other words, the Earth is encircled by a very thin atmosphere.

The atmosphere reflects the sun’s light. The atmosphere looks different from day to day, sometimes blues skies, sometimes cloudy skies. Space, on the other hand, doesn’t have air. That’s why the night sky is always pitch black.

The atmosphere is made up of many kinds of gases. However, two gases make up most of the atmosphere. About four-fifths (78%) is nitrogen, and about one-fifth (21%) is oxygen. The remaining 1% includes very small amounts of carbon dioxide, helium, methane, and other gases.