Phenomenology of ice formation in INTACC and SUCCESS

An analysis of both the INTACC and SUCCESS data sets is undertaken to assess ice formation phenomenology in light of recent laboratory and field studies. To aid in this analysis, the Asphericity Factor utilized as a threshold indicator for the presence of ice in previous work is now used as a continuous variable to indicate extent of glaciation. The INTACC data yield only one case of homogeneous nucleation. The bulk of the data suggest heterogeneous nucleation is dependent on particle number concentrations in the 0.1 to 0.3 μm size range. The SUCCESS data are in accord with this. A tentative rationalization of this phenomenology in terms of the chemical composition of this preferred size range is offered.