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At 20 °C and 101.325 kPa, dry air has a density of 1.2041 kg/m 3. At 70 °F and 14.696 psi, dry air has a density of 0.074887 lb/ft 3. The following table illustrates the air density–temperature relationship at 1 atm or 101.325 kPa: [citation needed]
K) specific gas constant for dry air ρa = P_a / (Rs_a * Tair) return ρa end # Wet air density ρ [kg/m3] # Tair air temperature in [Kelvin] # P absolute atmospheric pressure [Pa] function wet_air_density (RH, Tair, P) es = water_vapor_saturated_pressure (Tair, P) e = es * RH / 100 ρv = water_vapor_density (e, Tair) ρa = dry_air_density (P-e ...
Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude. The change of atmospheric pressure with altitude can be obtained from this equation: [2]
The saturation vapor density (SVD) is the maximum density of water vapor in air at a given temperature. [1] The concept is related to saturation vapor pressure (SVP). It can be used to calculate exact quantity of water vapor in the air from a relative humidity (RH = % local air humidity measured / local total air humidity possible ) Given an RH percentage, the density of water in the air is ...
This scaled quantity is known as virtual temperature, and it allows for the use of the dry-air equation of state for moist air. [5] Temperature has an inverse proportionality to density. Thus, analytically, a higher vapor pressure would yield a lower density, which should yield a higher virtual temperature in turn.
The Arden Buck equations are a group of empirical correlations that relate the saturation vapor pressure to temperature for moist air.The curve fits have been optimized for more accuracy than the Goff–Gratch equation in the range −80 to 50 °C (−112 to 122 °F).
Composition of dry atmosphere, by volume [ note 1] [ note 2]; Gas (and others): Various [1]: CIPM-2007 [2]: ASHRAE [3]: Schlatter [4]: ICAO [5]: US StdAtm76 [6]: Tap ...
The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. In other words, the density altitude is the air density given as a height above mean sea level .