acoular.tools.utils.mole_fraction_of_water_vapor¶

acoular.tools.utils.mole_fraction_of_water_vapor(h, t, p=101325)¶

Mole fraction of water vapor in the air for real gases.

Calculates the mole fraction of water vapor in air from the relative humidity, based on the equations provided in the appendix of [20] and the enhancement factors from [21].

Parameters:

hfloat

Relative humidity as a fraction [0,1].

tfloat

Thermodynamic temperature in K.

pfloat

Atmospheric pressure in Pa (default is the standard pressure 101325 Pa).

Returns:

float

Mole fraction of water vapor.

Notes

The mole fraction is calculated as:

\[x_w = h \cdot f \cdot \frac{p_{sv}}{p},\]

where:

• \(h\) is the relative humidity as a fraction [0,1].

• \(f\) is the enhancement factor:

  \[f = 1.00062 + 3.14 \times 10^{-8} \cdot p + 5.6 \times 10^{-7} \cdot t^2.\]

• \(p_{sv}\) is the saturation vapor pressure of water vapor in air:

  \[p_{sv} = \exp(A \cdot t^2 + B \cdot t + C + \frac{D}{t}),\]

  with the updated coefficients from [21]:

  \[\begin{split}A = 1.2378847 \times 10^{-5}, \\ B = -1.9121316 \times 10^{-2}, \\ C = 33.93711047, \\ D = -6.3431645 \times 10^3.\end{split}\]