Description
Compute mixing ratio \(w\) (g/kg) from pressure \(p\) (mb) and vapor pressure \(e\) (mb). \(e\) is calculated from temperature \(t\) (K) using the Hardy equation. \(\epsilon\) is the molar mass ratio of water to dry air (0.622).
Formula
$$
e = e_{sw} (t) \frac {RH} {100}\\
w = 1000 \epsilon \frac {e} {p - e}
$$
When used in calculating RH from dew point, \(e\) is calculated as:
$$
e = e_{sw} (dp)
$$
Source
Edit me