nucleationnoun [ U ]
uk/ˌnjuː.klɪˈeɪ.ʃən//ˌnuː.klɪˈeɪ.ʃən/specializedthe first step in the process of a substance changing from one state to another:
This section deals with the simplest nucleation event, namely the nucleation of solid crystals during the freezing of a pure metal.
In the context of air pollution, nucleation initiates the process by which gases are converted to small liquid droplets.