The Arden Buck equations are a group of empirical correlations that relate the
saturation vapor pressure
Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phas ...
to temperature for
moist air. The curve fits have been optimized for more accuracy than the
Goff–Gratch equation The Goff–Gratch equation is one (arguably the first reliable in history) amongst many experimental correlation proposed to estimate the saturation water vapor pressure at a given temperature.
Another similar equation based on more recent data is ...
in the range .
[Buck 1981]
A set of several equations were developed, each of which is applicable in a different situation.
Formula
The equations suggested by (which are modifications of the equations in ) are:
:
, over liquid water, > 0 °C
:
, over ice, < 0 °C
where:
* is the saturation vapor pressure in
hPa
* is the
exponential function
The exponential function is a mathematical function denoted by f(x)=\exp(x) or e^x (where the argument is written as an exponent). Unless otherwise specified, the term generally refers to the positive-valued function of a real variable, ...
* is the air temperature in degrees Celsius
Buck (1981) also lists enhancement factors for a temperature range of −80 to 50 °C (−112 to 122 °F) at pressures of 1,000 mb, 500 mb, and 250 mb. These coefficients are listed in the table below.
See also
*
Vapour pressure of water
*
Antoine equation
The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure substances. The Antoine equation is derived from the Clausius–Clapeyron relation. The equation was presented ...
*
Tetens equation The Tetens equation is an equation to calculate the saturation vapour pressure of water over liquid and ice. It is named after its creator, O. Tetens who was an early German meteorologist. He published his equation in 1930,Tetens, O. 1930. Über e ...
*
Lee–Kesler method
The Lee–Kesler method
allows the estimation of the saturated vapor pressure at a given temperature for all components for which the critical pressure ''P''c, the critical temperature ''T''c, and the acentric factor ''ω'' are known.
Equation ...
*
Goff–Gratch equation The Goff–Gratch equation is one (arguably the first reliable in history) amongst many experimental correlation proposed to estimate the saturation water vapor pressure at a given temperature.
Another similar equation based on more recent data is ...
Notes
References
*
*{{Citation
, last= Buck
, title= Buck Research CR-1A User's Manual, Appendix 1.
, year= 1996
, url= http://www.hygrometers.com/wp-content/uploads/CR-1A-users-manual-2009-12.pdf
External links
Web Page listing various vapor pressure equations(for below 0 °C)
Atmospheric thermodynamics
Psychrometrics