Looking Back: An Account of How Ice Nucleation by Bacteria Was Discovered (1963 to about Mid-1980s). Part II: Broadening the Scope

In Part I, we described the discoveries we and our associates made in the 1960s and 1970s about biological ice nucleating particles (bio-INPs). The bio-INPs are far more effective than mineral INPs at temperatures above −10°C. The bio-INPs were found in decayed vegetation and in ocean water, and then, bacteria were identified as being the most active source for this remarkable activity. In this Part II, we recount how, within a few years, the worldwide distribution of bio-INP sources was shown to correlate with climate zones, as was the abundance of INPs in precipitation. Oceanic sources were further studied, and the presence of bio-INPs in fog diagnosed. The potential for release of bio-INPs from the ground to the atmosphere was demonstrated. Bacterial INPs were found to play a crucial role in a plant’s frost resistance. These and other early developments of biological INPs are described. A bibliography of related recent literature is presented in the online supplemental material ( https://doi.org/10.1175/BAMS-D-23-0114.s1 ).