Saturation mixing ratio

From Glossary of Meteorology

saturation mixing ratio

A thermodynamic function of state; the value of the mixing ratio of saturated air at the given temperature and pressure.

This value may be read directly from a thermodynamic diagram. Without specific qualification, the saturation mixing ratio refers to saturation with respect to a plane surface of pure water. Saturation mixing ratios may also be specified with respect to a plane ice surface.