Psychrometric Formula

psychrometric formula

[¦sī·krə¦me·trik ′fȯr·myə·lə]
The semiempirical relation giving the vapor pressure in terms of the barometer and psychrometer readings.

Psychrometric Formula


a relationship that permits a determination of vapor pressure from the readings of dry-bulb and wet-bulb thermometers. Mathematically, it is expressed as e = E – AP(ttw), where e is the vapor pressure in the air, E is the saturation vapor pressure at temperature tw of

Figure 1. Dependence of the psychrometer constant A on the velocity of air flow past the thermometer bulb

the wet-bulb thermometer, t is the air temperature, P is the atmospheric pressure, and A is the psychrometer constant, which depends on the design of the psychrometer and, in a more direct way, on the velocity of air flow past the thermometer bulb (see Figure 1).

References in periodicals archive ?
Sanders, 1974: Method for obtaining wet-bulb temperatures by modifying the psychrometric formula.
The psychrometric formula relates this observed temperature depression and the temperature of the dry bulb to the quantity of moisture in the air.