# equivalent_potential_temperature¶

metpy.calc.equivalent_potential_temperature(pressure, temperature, dewpoint)[source]

Calculate equivalent potential temperature.

This calculation must be given an air parcel’s pressure, temperature, and dewpoint. The implementation uses the formula outlined in [Bolton1980]:

First, the LCL temperature is calculated:

$T_{L}=\frac{1}{\frac{1}{T_{D}-56}+\frac{ln(T_{K}/T_{D})}{800}}+56$

Which is then used to calculate the potential temperature at the LCL:

$\theta_{DL}=T_{K}\left(\frac{1000}{p-e}\right)^k \left(\frac{T_{K}}{T_{L}}\right)^{.28r}$

Both of these are used to calculate the final equivalent potential temperature:

$\theta_{E}=\theta_{DL}\exp\left[\left(\frac{3036.}{T_{L}} -1.78\right)*r(1+.448r)\right]$
Parameters: pressure (pint.Quantity) – Total atmospheric pressure temperature (pint.Quantity) – Temperature of parcel dewpoint (pint.Quantity) – Dewpoint of parcel pint.Quantity – The equivalent potential temperature of the parcel

Notes

[Bolton1980] formula for Theta-e is used, since according to [DaviesJones2009] it is the most accurate non-iterative formulation available.