earthkit.meteo.thermo.fieldlist.vapour_pressure_from_specific_humidity

earthkit.meteo.thermo.fieldlist.vapour_pressure_from_specific_humidity(q, p=None)

Compute the vapour pressure from specific humidity.

Parameters:

  • q (FieldList|Field) – Specific humidity (kg/kg).

  • p (FieldList|Field|Iterable[float]|float|None) – Pressure (Pa). If None, inferred from the field metadata of q. Otherwise, if q is a FieldList p must be a FieldList or an array-like of the same length as q. If q is a Field, p must be a single Field or a float.

Returns:

Vapour pressure (Pa). The result has the same type as the input q (FieldList or Field).

Return type:

FieldList|Field

The computation is based on the following formula [Wallace2006]:

\[e = \frac{pq}{\epsilon (1 + q(\frac{1}{\epsilon} -1 ))}\]

with \(\epsilon = R_{d}/R_{v}\) (see earthkit.meteo.constants.epsilon).