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At sea level, the atmosphere exerts pressure on Earth at a force of 14.7 pounds per square inch.
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Atmospheric Pressure

Pressure is an idea scientists use to describe how gases and liquids "push" on things. The atmosphere has pressure. If you imagine a column of air that is 1 inch square and goes from the Earth's surface all the way up through the atmosphere, the pressure of the air in that column is 14.7 pounds per square inch. Now that may seem like a lot of pressure pressing down on your body if you think of how many square inches it takes to cover your body! But pressure is a force that is spread out over an area. So all of that pressure is not a force pushing down, but a force spread over your entire skin, hair, fingernails and so on.

Atmospheric pressure is not always the same. If a low pressure system or a high pressure system is passing over your house, that will change the atmospheric pressure.

Air pressure also changes as you go up! The air pressure in Earth's atmosphere is pretty strong when you are near sea level. When you go higher up, in an airplane or to the top of a mountain, there is less pressure.

Temperature also affects atmospheric pressure. Warmer temperatures will make atmospheric pressure go up.

The highest recorded atmospheric pressure, 32.06 inches of Mercury, happened in Mongolia, December 19, 2001. The lowest pressure (outside of those measured in tornadoes) was 25.69 inches of Mercury in the Western Pacific during Typhoon Tip on October 12, 1979.

Atmospheric pressure is measured in many different units.

Last modified June 11, 2010 by Becca Hatheway.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA