Mixed-Phase Clouds: Observations and Modeling presents advanced research topics on mixed-phase clouds. As the societal impacts of extreme weather and its forecasting grow, there is a continuous need to refine atmospheric observations, techniques and numerical models. Understanding the role of clouds in the atmosphere is increasingly vital for current applications, such as prediction and prevention of aircraft icing, weather modification, and the assessment of the effects of cloud phase partition in climate models. This book provides the essential information needed to address these problems with a focus on current observations, simulations and applications. - Provides in-depth knowledge and simulation of mixed-phase clouds over many regions of Earth, explaining their role in weather and climate - Features current research examples and case studies, including those on advanced research methods from authors with experience in both academia and the industry - Discusses the latest advances in this subject area, providing the reader with access to best practices for remote sensing and numerical modeling

This volume outlines the fundamentals and applications of light scattering, absorption and polarization processes involving ice crystals.

Published results of observations of crystal habits, particle sizes and numbers of ice particles in clouds are summarized and discussed. There are systematic variations with cloud type, and in some instances, with cloud age and location within a cloud system. However, the body of data available is insufficient to formulate a climatology of ice cloud microphysics. The several measurement techniques in current use are evaluated, as are some of the techniques now under consideration for future use. The particle enhancement observed on some occasions is discussed, and the various theories accounting for it presented. Finally, recommendations are made concerning future field programs and theoretical studies required before accurate predictions of the ice cloud microphysical environment can be made. (Author).

Arctic single layer mixed-phase clouds were studied using a one-dimensional model that incorporated the adaptive habit growth model for ice microphysics. The base case was from the Indirect and Semi-Direct Aerosol Campaign, and it was perturbed over a range of cloud temperatures, ice nuclei concentrations, and large-scale subsidence velocities, quantities upon which mixed-phase cloud glaciation timescales are dependent. The focus of the study was quantifying mixed-phase cloud glaciation timescale dependence on these three parameters. To this end, a metric of liquid cloud evolution based on liquid water path changes was developed and used to characterize mixed-phase cloud evolution towards glaciation. Dependence of the metric on cloud temperatures from -30°C to -5°C, ice nuclei concentrations from 0.10 L-1 to 30 L-1 in a diagnostic nucleation scheme, and strong to moderate (observed) to no subsidence, with both spherical and habit-dependent ice crystal growth, was investigated. Spherical and habit-dependent ice crystal growth led to different relationships between critical ice nuclei concentration, the ice nuclei concentration above which a mixed-phase cloud glaciates, and cloud average temperature and subsidence strength. For spherical ice crystal growth, the relationship between critical ice nuclei concentration and cloud average temperature is monotonic, with the critical ice nuclei concentration decreasing with decreasing cloud average temperature. With strengthening subsidence, the critical ice nuclei concentration decreases for every cloud average temperature. For habit-dependent ice crystal growth, the relationship with cloud average temperature is not monotonic because ice crystals develop dendritic and columnar habits near -15°C and -7°C, respectively. At these two temperatures ice crystals grow faster and deplete more supercooled liquid water, leading to deep local minima in critical ice nuclei concentrations around these two temperatures. As for spherical growth, critical ice nuclei concentrations decrease with increasing subsidence for habit-dependent ice crystal growth. Habit-dependent ice crystal growth coupled with cloud average temperature, critical ice nuclei concentration, and subsidence strength lead to significant changes in Arctic mixed-phase cloud lifetimes.

This monograph offers a wide array of contemporary information on weather radar polarimetry and its applications. The book tightly connects the microphysical processes responsible for the development and evolution of the clouds’ bulk physical properties to the polarimetric variables, and contains the procedures on how to simulate realistic polarimetric variables. With up-to-date polarimetric methodologies and applications, the book will appeal to practicing radar meteorologists, hydrologists, microphysicists, and modelers who are interested in the bulk properties of hydrometeors and quantification of these with the goals to improve precipitation measurements, understanding of precipitation processes, or model forecasts.