mixing_ratio_from_relative_humidity#

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

Calculate the mixing ratio from relative humidity, temperature, and pressure.

Parameters:

  • pressure (pint.Quantity) – Total atmospheric pressure

  • temperature (pint.Quantity) – Air temperature

  • relative_humidity (array-like) – The relative humidity expressed as a unitless ratio in the range [0, 1]. Can also pass a percentage if proper units are attached.

  • 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 – Mixing ratio (dimensionless)

Examples

>>> from metpy.calc import mixing_ratio_from_relative_humidity
>>> from metpy.units import units
>>> p = 1000. * units.hPa
>>> T = 28.1 * units.degC
>>> rh = .65
>>> mixing_ratio_from_relative_humidity(p, T, rh).to('g/kg')
<Quantity(15.7296568, 'gram / kilogram')>

See also

relative_humidity_from_mixing_ratio, saturation_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).

\[RH = \frac{w}{\epsilon + w} \frac{\epsilon + w_s}{w_s}\]
\[\therefore w = \frac{\epsilon * w_s * RH}{\epsilon + w_s (1 - RH)}\]

  • \(w\) is mixing ratio

  • \(w_s\) is the saturation mixing ratio

  • \(\epsilon\) 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 (relative_humidity, temperature, pressure)

Examples using metpy.calc.mixing_ratio_from_relative_humidity#

Hydrostatic Thickness

Hydrostatic Thickness

Sounding Calculation Examples

Sounding Calculation Examples