Regimes of liquid-ice coexistence that may form in an adiabatic parcel ascending at constant velocity at freezing temperatures are investigated. Four zones with different microphysical structures succeeding one another along the vertical direction have been established. On the basis of a novel balance equation, analytical expressions are derived to determine the conditions specific for each of these zones. In particular, the necessary and sufficient conditions for formation of liquid water phase within an ascending parcel containing only ice particles are determined. The results are compared to findings reported in earlier studies. The role of the Wegener-Bergeron-Findeisen mechanism in the phase transformation is analyzed. The dependence of the phase relaxation time on height in the four zones is investigated on the basis of a novel analytical expression. The results obtained in the study can be instrumental for analysis and interpretation of observed mixed-phase clouds.
Bibliographical noteFunding Information:
This research was supported by the Israel Science Foundation (grant 1393/14), the Office of Science (BER), U.S. Department of Energy award DE-SC0006788 and the Binational US-Israel Science foundation (grant 2010446). Korolev’s participation was supported by Environment Canada. The authors express their gratitude to V. Phillips (University of Lund) and to anonymous reviewers. The supplemental data is available upon request (emails: Alexander.Khain@mail.huji.ac.il; Mark.Pinsky@mail.huji.ac.il).
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