psychrometric_constant#
- hydrometlib.evapotranspiration.psychrometric_constant(pa, lv)[source]#
Psychrometric constant (gamma) [kPa degC-1]
\[\gamma = \frac{1.013 \times 10^{-3} \cdot (p_a / 10)}{0.622 \, \lambda}\]where \(p_a\) is in hPa (divided by 10 to give kPa) and \(\lambda\) is the latent heat of vaporization.
References
FAO-56 Chapter 3 (eq. 8) https://www.fao.org/4/x0490e/x0490e07.htm#psychrometric%20constant%20(g)
- Parameters:
pa (
Expr) – Atmospheric pressure [hPa]lv (
Expr) – Latent heat of vaporization [MJ kg-1]
- Return type:
Expr- Returns:
Expression or Series to calculate gamma