Atmosphere (unit) 582780 224550330 2008-07-09T10:50:15Z Zorrobot 7218328 robot Modifying: [[uk:Атмосфера (одиниця)]] '''Standard atmosphere''' is a pressure defined as 101,325 [[Pascal (unit)|Pa]] and used as unit of [[pressure]] (symbol: atm). Standard atmosphere is a non-[[SI]] unit that is internationally recognized. The [http://www.bipm.org/jsp/en/ViewCGPMResolution.jsp?CGPM=10&RES=4 10th Conférence Générale des Poids et Mesures] (10th CGPM) adopted ''standard atmosphere'' for general use and affirmed its definition of being precisely equal to 1,013,250 [[dyne]]s per [[square centimeter]] (101,325&nbsp;[[Pascal (unit)|Pa]]). This value is intended to represent the mean atmospheric pressure at mean sea level at the latitude of [[Paris|Paris, France]], and as a practical matter, truly reflects the mean sea level pressure for many of the industrialized nations (those with latitudes similar to Paris). In [[chemistry]], the original definition of “Standard Temperature and Pressure” ([[standard conditions for temperature and pressure|STP]]) was a reference temperature of 0&nbsp;[[°C]] (273.15&nbsp;[[kelvin|K]]) and pressure of 101.325&nbsp;[[kilopascal|kPa]] (1 atm). However, in 1982, the [[International Union of Pure and Applied Chemistry]] (IUPAC) recommended that for the purposes of specifying the physical properties of substances, “''the standard pressure''” should be defined as precisely 100&#160;kPa (&asymp;750.062&#160;Torr).<ref>IUPAC.org, Gold Book, ''[http://goldbook.iupac.org/S05921.html Standard Pressure]''</ref> ==Pressure units and equivalencies == {{Pressure Units}} A pressure of 1&nbsp;atm can also be stated as: :&equiv;1.013&nbsp;25 [[bar (unit)|bar]] :&equiv;101.325 [[kilopascal|kPa]] :&equiv;1013.25 [[millibar]]s (mbar, also mb) or [[hectopascal]]s (hPa) :&equiv;760 [[torr]]<sup> [B]</sup> :&asymp;760.001 mm-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available<sup> [B, C]</sup> :&asymp;29.9213 in-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available<sup> [C]</sup> :&asymp;1.033&nbsp;227&nbsp;452&nbsp;799&nbsp;886 [[kgf]]/cm² :&asymp;1.033&nbsp;227&nbsp;452&nbsp;799&nbsp;886 [[technical atmosphere]] :&asymp;1033.227&nbsp;452&nbsp;799&nbsp;886 cm–H<sub>2</sub>O, 4 °C<sup> [A]</sup> :&asymp;406.782&nbsp;461&nbsp;732&nbsp;2385 in–H<sub>2</sub>O, 4 °C<sup> [A]</sup> :&asymp;14.695&nbsp;948&nbsp;775&nbsp;5134 [[pound-force per square inch|pounds-force per square inch]] (psi) :&asymp;2116.216&nbsp;623&nbsp;673&nbsp;94 pounds-force per square foot psf) :Notes: :<sup>A</sup> This is the customarily-accepted value for cm–H<sub>2</sub>O, 4 °C. It is precisely the product of 1&nbsp;kg-force per square centimeter (one technical atmosphere) times 1.013&nbsp;25 (bar/atmosphere) divided by 0.980&nbsp;665 (one gram-force). It is not accepted practice to define the value for water column based on a true physical realization of water (which would be 99.997&nbsp;495% of this value because the true maximum density of [[Vienna Standard Mean Ocean Water]] is 0.999&nbsp;974&nbsp;95 kg/l at 3.984 °C). Also, this “physical realization” would ''still'' ignore the 8.285&nbsp;cm–H<sub>2</sub>O reduction that would actually occur in a true physical realization due to the vapor pressure over water at 3.984 °C. :<sup>B</sup> Torr and mm-Hg, 0°C are often taken to be identical. For most practical purposes (to 5 significant digits), they are interchangeable. :<sup>C</sup> [[NIST]] value of 13.595&nbsp;078(5) g/ml assumed for the density of Hg at 0 °C ==Other applications== In the [[United Kingdom]], [[scuba diver]]s and others often use the word ''atmosphere'' loosely (the correct term is "ambient pressure") to mean 1 [[bar (unit)|bar]] (1000 millibars, or 100<font size="-1">&nbsp;</font>000&nbsp;[[pascal (unit)|Pa]]). The unit [[technical atmosphere]] (at) is roughly equal to the gauge pressure under 10&nbsp;[[metre|m]] of water; 1&nbsp;at = 98066.5&nbsp;Pa. ==See also== *[[Standard conditions for temperature and pressure]] == References == {{reflist}} [[Category:Units of pressure]] [[Category:Atmosphere]] [[Category:Chemical engineering]] [[Category:Environmental engineering]] [[Category:Mechanical engineering]] [[Category:Physical chemistry]] [[Category:Standards]] [[Category:Thermodynamics]] [[be-x-old:Атмасфэра (адзінка вымярэньня)]] [[bs:Standardna atmosfera]] [[bg:Атмосфера (единица)]] [[ca:Atmosfera (unitat)]] [[cs:Atmosféra (jednotka)]] [[da:Atmosfære (enhed)]] [[de:Physikalische Atmosphäre]] [[et:Atmosfäär (ühik)]] [[el:Ατμόσφαιρα (μονάδα)]] [[es:Atmósfera (unidad)]] [[eu:Atmosfera (unitatea)]] [[fa:اتمسفر (واحد)]] [[fr:Atmosphère (unité)]] [[ko:기압]] [[hr:Standardna atmosfera]] [[it:Atmosfera (unità di misura)]] [[he:אטמוספירה (מידה)]] [[lv:Atmosfēra (mērvienība)]] [[lt:Atmosfera (matavimo vienetas)]] [[hu:Atmoszféra (mértékegység)]] [[nl:Atmosfeer (eenheid)]] [[no:Standardatmosfære]] [[nn:Standardatmosfære]] [[pl:Atmosfera fizyczna]] [[pt:Atmosfera padrão]] [[ru:Атмосфера (единица измерения)]] [[sk:Atmosféra (jednotka)]] [[sl:Atmosfera (enota)]] [[sv:Atmosfär (tryckenhet)]] [[uk:Атмосфера (одиниця)]] [[zh:标准大气压]]