Wet-bulb temperature

Wet-bulb temperature - there are several meanings of this term:

The temperature read from a wet bulb thermometer,
Isobaric wet-bulb temperature: the temperature an air parcel would have if cooled adiabatically to saturation at constant pressure by evaporation of water into it, all latent heat being supplied by the parcel;
Adiabatic wet-bulb temperature: the temperature an air parcel would have if cooled adiabatically to saturation and then compressed adiabatically to the original pressure in a moist-adiabatic process (AMS Glossary).

Wet-bulb temperature measured by wet bulb thermometer

Wet-bulb temperature is measured using a psychrometric chart (or via complex calculation).

$e_s = 6.112 \exp \left( {17.67T \over T+243.5} \right)$

$e_w = 6.112 \exp \left( {17.67T_w \over T_w+243.5} \right)$

$e=e_w-p_{sta} \left(T-T_w\right) 0.00066 \left[1+(0.00115 T_w) \right]$

$RH= 100 {e \over e_s}$

$T_d={243.5 \log(e/6.112) \over 17.67 - \log(e/6.112)}$

where:

RH is relative humidity and

T d

is dew point in degrees Celsius

T

and

T w

are the dry-bulb and wet-bulb temperatures respectively in degrees Celsius

e s

,

e w

and

e

are the saturated water vapour pressure at the dry-bulb, wet-bulb at saturation pressure and normalized to sea level pressure wet-bulb (hPa)

for greater accuracy use the Arden Buck Equation to find the water vapour pressures

wet bulb globe temperature.

See also

wet-bulb potential temperature
Dewpoint
Wet Bulb Chart for Snow Making (Fahrenheit)
http://www.srh.noaa.gov/elp/wxcalc/formulas/rhTdFromWetBulb.html
http://amsglossary.allenpress.com/glossary/search?p=1&query=wet-bulb+temperature
http://www.theweatherprediction.com/habyhints/170/ (Shortcut to estimate wet bulb temperature)

Atmospheric thermodynamics

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Wet-bulb_temperature". A list of authors is available in Wikipedia.