The saturation vapor pressure is the vapor pressure of water when air is saturated with water (having the maximum amount of water vapor that air can hold for a given temperature and pressure). It is the vapor pressure usually found over liquid water, and is a dynamicequilibrium where condensation of water equals the evaporation of water. In general, the higher the temperature, the more water vapor the air can hold. The same holds true with increases in pressure. When air is at saturation vapor pressure, it is said to be at the dew point. Thus, at saturation vapor pressure, air has a relative humidity of 100%, and condensation occurs. The vapor pressure is the pressure (if the vapor is mixed with other gases, the partial pressure) of a vapor. ... A falling water droplet Water (from the Anglo-Saxon and Low German wæter) is a colourless, tasteless, and odourless substance that is essential to all known forms of life and is the most universal solvent. ... The term saturation generally means thoroughly full, and can refer to the following: In chemistry, see saturation (chemistry) for a number of meanings. ... General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface, it is said to have evaporated. ... The word dynamics can refer to: a branch of mechanics; see dynamics (mechanics) the volume of music; see dynamics (music) When used referring to mechanics, it is referring to the study of the motion of both rigid bodies and particles. ... For the 2002 science fiction movie see Equilibrium (2002 movie) Equilibrium or balance is any of a number of related phenomena in the natural and social sciences. ... The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapor component to condense into water, called dew. ... Relative humidity is the ratio of the current vapor pressure of water in any gas (especially air) to the vapor pressure at which the gas would become saturated at the current temperature, normally expressed as a percentage (of what to what?). Equivalently, it is the ratio of the current mass...
The term saturationvaporpressure arose because it was believed that this was the maximum amount of watervapor that could be dissolved in air.
John Dalton concluded that the vaporpressure of water in air is independent of the existence of the air (Brutsaert 1991, Cardwell 1968, Greenaway 1966, Ostwald 1891, Dalton 1803).
This is the equilibrium 'student' pressure, analogous to the equilibrium or saturationvaporpressure.
There is a large number of saturationvaporpressure equations used to calculate the pressure of watervapor over a surface of liquid water or ice.
It is important to note that in the upper troposphere, watervapor measurements reported in the WMO convention as relative humidity with respect to liquid water depend critically on the saturationvaporpressure equation that was used to calculate the RH value.
Goff, J. Saturationpressure of water on the new Kelvin temperature scale, Transactions of the American society of heating and ventilating engineers, pp 347-354, presented at the semi-annual meeting of the American society of heating and ventilating engineers, Murray Bay, Que.
Feeds |
Contact