Virtual temperature

The virtual temperature (T_v) of an air parcel is the temperature that dry air would have if its pressure and density were equal to those of a sample of moist air. [cite book
last = Bailey
first = Desmond T.
others = John Irwin
title = Meteorological Monitoring Guidance for Regulatory Modeling Applications
origyear = 1987
origmonth = 6
url = http://www.epa.gov/scram001/guidance/met/mmgrma.pdf
year = 2000
month = 2
publisher = United States Environmental Protection Agency
location = Research Triangle Park, NC
id = EPA-454/R-99-005
pages = p. 9-14
chapter = Upper-air Monitoring] The virtual temperature allows the use of the dry-air equation of state for moist air, except with T replaced by T_v. [cite web
url=http://amsglossary.allenpress.com/glossary/search?id=virtual-temperature1
title=AMS Glossary
accessdate=2007-05-07
publisher=American Meteorological Society] A formula for the virtual temperature $T\_v$ is

$\{T\_v\}\; =\; frac\{T\}\{1-frac\{e\}\{p\}(1-varepsilon)\},\; ,$

where $T$ is the ambient temperature, $e$ is the partial pressure of the variable gas, $p$ is the pressure, and $epsilon$ is the molar mass ratio of the variable gas to the dry gas, and for Earth is 0.622.

References