Atmospheric pressure

Atmospheric pressure is the pressure above any area in the Earth's atmosphere caused by the weight of air. Standard atmospheric pressure (atm) is discussed in the next section.

Related Topics:
Pressure - Earth's atmosphere - Weight - Air

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Air masses are affected by the general atmospheric pressure within the mass, creating areas of high and low pressure.

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As elevation increases, fewer air molecules are above. Therefore, atmospheric pressure decreases with increasing altitude. The following relationship is a first-order approximation:

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:log_{10} P pprox {5-{h over 15500}},

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where P is the pressure in pascals and h the height in metres. This shows that the pressure at an altitude of 31 km is about 10(5-2) Pa = 1000 Pa, or 1% of that at sea level1.

Related Topics:
Pascal - Metre - Km - 1

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A column of air, 1 square inch in cross section, measured from sea level to the top of the atmosphere would weigh approximately 14.7 lbf. A 1 m2 column of air would weigh about 100 kilonewtons. See density of air.

Related Topics:
Kilonewton - Density of air

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