# Saturation equivalent potential temperature

From Glossary of Meteorology

## saturation equivalent potential temperature

Saturation equivalent potential temperature (represented as θ

Reference:_{es}) is a special case of equivalent potential temperature (θ_{e}) computed by assuming an air parcel is saturated (i.e.,*r*=*r*in the equation for θ_{sat}_{e})and thus represents the theoretical maximum θ_{e}. Both θ_{es}and θ_{e}are themselves special cases of potential temperature (θ), accounting for the latent heat release due to condensation of water vapor by lifting the parcel to a new temperature and pressure via a pseudoadiabatic process prior to computing the potential temperature. Hence, θ_{es}is conserved for a reversible moist adiabatic process. The relationship between the three types of potential temperature can be described as follows, where*r*represents the parcel water vapor mixing ratio and*r*is the saturation value of water vapor mixing ratio based on the parcel temperature and pressure:_{sat}

r=r(saturated environment): θ_{sat}_{e}= θ_{es},

r= 0 (dry environment): θ_{e}= θ, and0 <

r<r(unsaturated moist parcel): θ < θ_{sat}_{e }< θ_{es}.

*Atmospheric Thermodynamics*. Oxford University Press, 293–294.

*(term edited 8/22/2014)*