relative_humidity_from_specific_humidity#

metpy.calc.relative_humidity_from_specific_humidity(pressure, temperature, specific_humidity, *, phase='liquid')[source]#

Calculate the relative humidity from specific humidity, temperature, and pressure.

Parameters:

  • pressure (pint.Quantity) – Total atmospheric pressure

  • temperature (pint.Quantity) – Air temperature

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

  • 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 – Relative humidity

Examples

>>> from metpy.calc import relative_humidity_from_specific_humidity
>>> from metpy.units import units
>>> relative_humidity_from_specific_humidity(1013.25 * units.hPa,
...                                          30 * units.degC, 18/1000).to('percent')
<Quantity(68.4991531, 'percent')>

See also

relative_humidity_from_mixing_ratio

Notes

Employs [WMO8] eq. 4.A.16 as derived from WMO relative humidity definition based on vapor partial pressures (eq. 4.A.15).

\[RH = \frac{w}{\epsilon + w} \frac{\epsilon + w_s}{w_s}\]

given :math: w = frac{q}{1-q}

  • \(w\) is mixing ratio

  • \(w_s\) is the saturation mixing ratio

  • \(q\) is the specific humidity

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

  • \(RH\) is relative humidity as a unitless ratio

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

Examples using metpy.calc.relative_humidity_from_specific_humidity#

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Isentropic Analysis

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