dewpoint_from_specific_humidity

metpy.calc.dewpoint_from_specific_humidity(*args, **kwargs)

Calculate the dewpoint from specific humidity and pressure.

Parameters:

• pressure (pint.Quantity) – Total atmospheric pressure

• temperature (pint.Quantity, optional) – Air temperature. Unused in calculation, pending deprecation

• specific_humidity (pint.Quantity) – Specific humidity of air

Returns:

pint.Quantity – Dew point temperature

Examples

>>> from metpy.calc import dewpoint_from_specific_humidity
>>> from metpy.units import units
>>> dewpoint_from_specific_humidity(1000 * units.hPa, 5 * units('g/kg'))
<Quantity(3.79314079, 'degree_Celsius')>

Changed in version 1.6: Made temperature arg optional, to be deprecated

Changed in version 1.0: Changed signature from (specific_humidity, temperature, pressure)

See also

relative_humidity_from_mixing_ratio, dewpoint_from_relative_humidity, dewpoint

Notes

Employs [WMO8] eq 4.A.6,

\[e = \frac{w}{\epsilon + w} p\]

with

\[w = \frac{q}{1-q}\]

• \(q\) is specific humidity

• \(w\) is mixing ratio

• \(\epsilon\) is the molecular weight ratio of vapor to dry air

to calculate vapor partial pressure \(e\) for dewpoint calculation input. See dewpoint() for additional information.