A nucleation event is the process of condensation or aggregation (gathering) that results in the formation of larger drops or crystals around a material that acts as a structural nucleus around which such condensation or aggregation proceeds. Moreover, the introduction of such structural nuclei can often induce the processes of condensation or crystal growth. Accordingly, nucleation is one of the ways that a phase transition can take place in a material.

In addition to an importance in explaining a wide variety of geophysical and geochemical phenomena—including crystal formation—the principles of nucleation were used in cloud seeding weather modification experiments where nuclei of inert materials were dispersed into clouds with the hopes of inducing condensation and rainfall.

During a phase transition, a material changes from one form to another. For example, ice melts to form liquid water, or a liquid boils to form...