mixing_ratio_from_relative_humidity#

metpy.calc.mixing_ratio_from_relative_humidity(pressure, temperature, relative_humidity)[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.

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(15.7646969, '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).

$$RH=\frac{w}{ϵ+w}\frac{ϵ+w_s}{w_s}$$

$$\therefore w=\frac{ϵ\ast w_s\ast RH}{ϵ+w_s(1-RH)}$$

• $w$ is mixing ratio

• $w_s$ is the saturation mixing ratio

• $ϵ$ 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#

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