Should wet growth begin, a much lower liquid water content will be required to return to dry growth. The inherent instability of an ice dendrite growing from an underlying ice surface into a supercooled liquid above in quasi-steady state resulting from shear flow and the arrival of supercooled droplets. Add to this uncertainties concerning the impurity and ice defect structure and the true nature of the problem becomes evident. The simplicity of the diffusion chamber approach is to be contrasted with the full simulation approach of the riming wind tunnel or rotation experiment. Riming surface numerical simulation is a brave attempt but fraught with uncertainties with so many unknown physical and chemical processes on the scale of an individual droplet.
Nevertheless progress is significant.