Atmospheric pressure

Static pressure exerted by the weight of the Earth's atmosphere

Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as 101.325 kPa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, 760 torr (or about 760 mmHg), about 29.9212 inHg, or about 14.696 psi. The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately one atm.

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