Virtual temperature (TV)

virtual temperature
(Also called density temperature.) The virtual temperature Tv = T(1 + rv/ ε)/(1 + rv),
where rv is the mixing ratio and
ε is the ratio of the gas constants of air and water vapor, ≈ 0.622.

The virtual temperature allows the use of the dry-air equation of state for moist air,
except with T replaced by Tv. Hence the virtual temperature is the temperature that dry air
would have if its pressure and density were equal to those of a given sample of moist air.

For typical observed values of rv, the virtual temperature may be approximated by
Tv = (1 + 0.61 rv) T.

Some authors incorporate the density increment due to liquid or solid water into virtual temperature,
in which case the definition becomes Tv = T(1 + rv/ε)/(1 + rv + rl) ≈ T(1 + 0.61rv - rl),
where rl is the liquid or liquid plus solid water mixing ratio.

HS     surface orography (m)
PS     surface pressure (Pa)
P     pressure (Pa)
DP   delta pressure (Pa)
TV   virtual temperature (K)
T     sensible temperature (K)
Q     specific humidity (kg/kg)
RH  relative humidity (%)
U     zonal wind (m/s)
V     meridional wind (m/s)
DIV  divergence (m/s**2)
VOR   vorticity (m/s**2)
Q2    tracer 2 (kg/kg)
Q3    tracer 3 (kg/kg)