bjones
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Air is a general term applied to the mixture of gases that compose the Earth’s atmosphere. The atmosphere plays several important roles in the survival of all living species. Air not only contains the gases that both plants and animals breathe, but it protects life from the powerful radiation of the sun. Without the atmosphere, our planet would range from extremely hot where the sun hits it, to extremely cold where the sun isn’t. Animals use the oxygen in the atmosphere to breathe. Oxygen is a basic ingredient that animals need to sustain life. Plants use the carbon dioxide in the air to complete their life cycles. Both plants and animals help to create air because both types of life exhale or expel gases into the air. Animals exhale carbon dioxide and plants expel oxygen.
Air is composed of hundreds of different gases, but it is the top four that play the key roles in life. Nitrogen is the most abundant gas in the air. Air is just over 78 percent Nitrogen. Although we don’t use the nitrogen in the air, all life is partially made from it. The next abundant gas is Oxygen, at almost 21 percent. Argon is third, at .93 percent, and Carbon dioxide comes in fourth, at .04 percent. Other gases in air include Neon, Helium, Methane, Krypton, Hydrogen, Nitrous oxide, and Xenon.
The air is made of 5 distinct layers, and it gets thicker the closer it is to the surface of the Earth. The troposphere is the only layer that most of us ever reach. It is upward to a maximum of 56,000 feet. Above the troposphere are the stratosphere, mesosphere, thermosphere, and exosphere.
 Posted 5372 day ago
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