University of Illinois Extension

Under An Ocean of Air Pressure

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We don’t think about it, but we are actually living at the bottom of a large pool of air. This large pool of air is called the atmosphere. It is made up of mostly colorless, odorless gases. These include nitrogen, oxygen, and carbon dioxide.

The weight of all this air weighing down on us is what’s known as air pressure. The more air that is above us, the higher the air pressure will be. At sea level, the average air pressure is about 15 pounds for every square inch of surface area. At greater heights, the air pressure is lower, because there’s less air above weighing down. If you stand on top of Mount Everest, which is over 29,000 feet above sea level, the air pressure is only about 30 percent of sea level air pressure.

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