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$Q$ surface specific humidity

$Q_{sat}$ saturated surface humidity (calculated in constant\_veg:qsatcalc)

$P$ surface pressure

$h_r$ relative humidity of air

\begin{equation}
{h_{{r}}=\frac{Q\cdot P/{(0{.}{622}+0{.}{378}\cdot Q)}}{Q_{{{{sat}}}}\cdot P/{(0{.}{622}+0{.}{378}\cdot Q_{{{{sat}}}})}}}
\end{equation}
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