virtual_temperature_from_dewpoint#

metpy.calc.virtual_temperature_from_dewpoint(pressure, temperature, dewpoint, molecular_weight_ratio=0.6219569100577033, *, phase='liquid')[source]#

Calculate virtual temperature.

This calculation must be given an air parcel’s temperature and mixing ratio. The implementation uses the formula outlined in [Hobbs2006] pg.80.

Parameters:

  • pressure (pint.Quantity) – Total atmospheric pressure

  • temperature (pint.Quantity) – Air temperature

  • dewpoint (pint.Quantity) – Dewpoint temperature

  • molecular_weight_ratio (pint.Quantity or float, optional) – The ratio of the molecular weight of the constituent gas to that assumed for air. Defaults to the ratio for water vapor to dry air. (\(\epsilon\approx0.622\))

  • phase ({'liquid', 'solid', 'auto'}) – Where applicable, adjust assumptions and constants to make calculation valid in 'liquid' water (default) or 'solid' ice regimes. 'auto' will change regime based on determination of phase boundaries, eg temperature relative to freezing.

Returns:

pint.Quantity – Corresponding virtual temperature of the parcel

Examples

>>> from metpy.calc import virtual_temperature_from_dewpoint
>>> from metpy.units import units
>>> virtual_temperature_from_dewpoint(1000 * units.hPa, 30 * units.degC, 25 * units.degC)
<Quantity(33.6680183, 'degree_Celsius')>

Notes

\[T_v = T \frac{\text{w} + \epsilon}{\epsilon\,(1 + \text{w})}\]

Changed in version 1.0: Renamed mixing parameter to mixing_ratio