Overview of the Problems in the Physics of Mixed-Phase Clouds. (Invited Presentation)

This presentation aims to summarize a set of problems in the physics of mixed-phase clouds and identify directions for future research.

The theoretical description of mixed-phase clouds, along with observations and laboratory examination, continues to be a challenging issue in cloud physics. Recent progress enabled the formulation of a set of problems in the physics of mixed-phase clouds. The existing theoretical framework describing the evolution of the mixed-phase environment employs assumptions that did not receive sufficient laboratory or observational validation. This primarily refers to the assumptions of: (1) regular condensation, (2) homogeneity of mixed-phase environment and (3) sphericity of ice particles, (4) effect of large and small scale turbulence on the mixed-phase environment. The existing assumptions may result in a significant bias of cloud endurance, radiation fluxes, and precipitation formation in numerical weather predictions and climate simulations.

The limitations of the existing techniques used for observations of mixed-phase clouds are discussed. Currently, the capability of the principles behind the measurements utilized in today’s in-situ instrumentation has reached its upper limits. Relying on existing principles will continue to reproduce the same results with the same limitations. This underscores the urgent need for the development of observational techniques based on new principles of measurement. A set of requirements for the next generation of microphysical instrumentation is discussed, highlighting the importance of advancing research.

There is a strong need for feedback from laboratory studies to validate the developed theoretical framework of mixed-phase clouds and identify its weaknesses. Laboratory measurements of the fundamental parameters of mixed-phase environments such as glaciating time and time of-phase relaxation remain unaddressed. Experimental characterization of the Wegener-Bergeron-Findeisen (WBF) process under different environmental conditions is one of the highest priorities of experimental studies of mixed-phase clouds. The absence of laboratory facilities focused on studies of mixed-phase environments, along with the geophysical significance of mixed-phase clouds, underscores the necessity of international collaboration to address this issue.