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The standard atmosphere was originally defined as the pressure exerted by a 760 mm column of mercury at 0 °C (32 °F) and standard gravity (g n = 9.806 65 m/s 2). [2] It was used as a reference condition for physical and chemical properties, and the definition of the centigrade temperature scale set 100 °C as the boiling point of water at this pressure.
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 Pa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, [1] 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. [2]
JB2008 is a newer model of the Earth's atmosphere from 120 km to 2000 km, developed by the US Air Force Space Command and Space Environment Technologies taking into account realistic solar irradiances and time evolution of geomagnetic storms. [14] It is most useful for calculating satellite orbital decay due to atmospheric drag. Both CIRA 2012 ...
1.5 psi Pressure increase per meter of a water column [26] 10 kPa 1.5 psi Decrease in air pressure when going from Earth sea level to 1000 m elevation [citation needed] +13 kPa +1.9 psi High air pressure for human lung, measured for trumpet player making staccato high notes [48] < +16 kPa +2.3 psi
The units of atmospheric pressure commonly used in meteorology were formerly the bar (100,000 Pa), which is close to the average air pressure on Earth, and the millibar. Since the introduction of SI units, meteorologists generally measure atmospheric pressure in hectopascals (hPa), equal to 100 pascals or 1 millibar.
A standard reference value for air pressure: Standard atmosphere (unit), a standard pressure that approximates atmospheric pressure value at sea level; Standard atmospheric pressure, other reference values; One of various static atmospheric models of how atmospheric pressure, density, and temperature vary with altitude, such as:
Pressure units Pascal Bar Technical atmosphere Standard atmosphere Torr Pound per square inch (Pa) ... 1 atm ≡ 101 325: ≡ 1.013 25: 1.0332 — 760 14.695 948 775 ...
Values of ρ b of b = 1 through b = 6 are obtained from the application of the appropriate member of the pair equations 1 and 2 for the case when h = h b+1. [ 2 ] In these equations, g 0 , M and R * are each single-valued constants, while ρ , L , T and h are multi-valued constants in accordance with the table below.