psychrometric_vapor_pressure_wet¶

metpy.calc.psychrometric_vapor_pressure_wet(dry_bulb_temperature, wet_bulb_temperature, pressure, psychrometer_coefficient=<Quantity(0.000621, '1 / kelvin')>)[source]¶

Calculate the vapor pressure with wet bulb and dry bulb temperatures.

Parameters:	dry_bulb_temperature (pint.Quantity) – Dry bulb temperature wet_bulb_temperature (pint.Quantity) – Wet bulb temperature pressure (pint.Quantity) – Total atmospheric pressure psychrometer_coefficient (pint.Quantity) – Psychrometer coefficient
Returns:	pint.Quantity – Vapor pressure

Notes

\[e' = e'_w(T_w) - A p (T - T_w)\]

\(e'\) is vapor pressure
\(e'_w(T_w)\) is the saturation vapor pressure with respect to water at temperature \(T_w\)
\(p\) is the pressure of the wet bulb
\(T\) is the temperature of the dry bulb
\(T_w\) is the temperature of the wet bulb
\(A\) is the psychrometer coefficient

Psychrometer coefficient depends on the specific instrument being used and the ventilation of the instrument.

References

[12]	WMO GUIDE TO METEOROLOGICAL INSTRUMENTS AND METHODS OF OBSERVATION WMO-No.8 (2008 edition, Updated in 2010) : PART 4 https://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.html

[13]	Fan, Jinpeng. “Determination of the psychrometer coefficient A of the WMO reference psychrometer by comparison with a standard gravimetric hygrometer.” Journal of Atmospheric and Oceanic Technology 4.1 (1987): 239-244.