Mixed nucleus

From Glossary of Meteorology

mixed nucleus

A cloud condensation nucleus (CCN) composed of both soluble hygroscopic matter and insoluble, possibly wettable, matter.

Its mixed composition probably results from a coagulation process or from cycles of condensation and evaporation, possibly involving chemical reactions. When applied to natural ice nuclei or cloud seeding nuclei (as silver iodide), the term implies the presence of a soluble component that leads to condensation prior to initiation of freezing.