Heymsfield, A. J., Knight, C. A., & Dye, J. E. (1979). Ice initiation in unmixed updraft cores in northeast Colorado cumulus congestus clouds. Journal Of The Atmospheric Sciences, 36, 2215-2229. doi:10.1175/1520-0469(1979)036<2216:IIIUUC>2.0.CO;2