by Judith Curry

Our new book is now published.

Thermodynamics, Kinetics and Microphysics of Clouds by Vitaly I. Khvorostyanov and Judith Curry. Look Inside at amazon.com.

Excerpts from the Preface:

Cloud microphysics is a branch of cloud physics that studies initiation, growth and dissipation of cloud and precipitation particles. Cloud microphysics is governed by the thermodynamic and kinetic processes in clouds. The field of cloud microphysics has been intensively developed since the 1940’s when the first successful experiments on cloud seeding were performed. The field has received additional impetus in recent years from the challenges associated with forecasting precipitation and understanding aerosol-cloud interactions in context of climate change and feedback processes.

Thermodynamics, Kinetics and Microphysics of Clouds extends the subject of cloud microphysics beyond previous treatments. The goals and contents of this book are formulated to:

Present in compact form the major thermodynamic relations and kinetic equations required for theoretical consideration of cloud microphysics;

Review the currently known states of water in liquid, crystalline and amorphous forms, and the conceptual modern theories of water and equations of state for water in various states;

Formulate a closed system of equations that describe kinetics of cloud microphysical processes and is suitable both for analytical studies and for inclusion in numerical models;

Derive from theory generalized analytical parameterizations for aerosol deliquescence, hygroscopic growth, efflorescence, and for drop activation and ice nucleation in various modes;

Demonstrate that these theoretical parameterizations generalize and unify previous parameterizations and include them as particular cases; express previous empirical parameters via atmospheric and aerosol parameters and theoretical quantities;

Derive the kinetic equations of stochastic condensation and coagulation and obtain their analytical solutions that reproduce the observed drop and crystal size spectra; express parameters of empirical distributions from theory;

Outline a path for future generalizations of the kinetic equations of cloud microphysics based on the Chapman-Kolmogorov and Fokker-Planck equations.

In addition to advancing our basic understanding of cloud microphysical processes, the theoretical approach employed in this book supports the explanation and interpretation of laboratory and field measurements in context of instrument capabilities and limitations and motivates the design of future laboratory and field experiments. In the context of models that include cloud processes, ranging from small-scale models of clouds and atmospheric chemistry to global weather and climate models, the unified theoretical foundations presented here provide the basis for incorporating cloud microphysical processes in these models in a manner that represent the process interactions and feedback processes over the relevant range of environmental and parametric conditions. Further, the analytical solutions presented here provide the basis for computationally efficient parameterizations that include the relevant parametric dependencies.

This book incorporates the heritage of Russian cloud physics that introduced and developed the kinetic equations for drop and crystal diffusion growth, the fast numerical algorithms for their solutions, and stochastic approach to cloud microphysical processes. This Russian heritage is combined with the best knowledge of cloud microphysics acquired and described in the western literature over several decades. A large amount of the material presented in this book is based on original work conducted jointly by the authors over almost two decades. Some of this research has been published previously in journal articles, and a large fraction of material is being published in the book for the first time, notably the parameterization of heterogeneous ice nucleation and the theory of aerosol deliquescence and efflorescence.

Integration of Russian and Western perspectives on cloud physics was facilitated by the 1972 bilateral treaty between the U.S. and USSR on Agreement and Cooperation in the Field of Environmental Protection, specifically under Working Group VIII – The Influence of Environmental Change on Climate. Its regular meetings and exchanges of delegations and information promoted international collaboration, provided the foundation for long-term cooperation and outlined proposals for joint research. With the advent of the World Climate Research Programme (WCRP) in 1980, both Khvorostyanov and Curry subsequently became members of WCRP Working Group on Radiative Fluxes, which later became the Radiation Panel of the Global Water and Energy Exchange Experiment (GEWEX). The GEWEX Radiation Panel had regular annual meetings (where the authors participated and met), which initiated the collaboration that has lasted for almost two decades, resulted in more than 30 joint publications, and culminated in this book.

This book bridges Russian and Western perspectives of cloud physics. Khvorostyanov’s involvement in the evolution of the Russian school of cloud physics includes development of cloud models with spectral bin microphysics and applications to cloud seeding and cloud-radiation interactions. Curry’s early cloud microphysics research focused on aircraft observations of cloud microphysics and development of parameterizations for cloud and climate models. Over the past 18 years, Khvorostyanov and Curry have collaborated on a range of cloud microphysical topics of relevance to understanding and parameterizing cloud processes for cloud and climate models, that integrate the Russian perspectives on cloud microphysics into the broader community, and combine the eastern and western approaches to cloud microphysics. In addition to summarizing and integrating these perspectives and the broad body of recent research in cloud microphysics, throughout the book there are a number of new results as well as extensions and generalizations of existing ones.

The table of contents can be downloaded here toc

Correspondence principle

The integrating framework of the book is the correspondence principle. Excerpts from section 1.2:

A framework for pursuing this strategy is the correspondence principle, a major principle in physics. The correspondence principle was formulated by Niels Bohr in 1913 in developing his model of the atom and was later generalized in order to explain the correspondence to, and remove the contradictions between, the new quantum mechanics and the old classical physics. Subsequently, the correspondence principle has been generalized over several decades and extended to other phenomena in physics and other sciences. The correspondence principle states that a new theory or parameterization should not reject the previous correct theory or parameterization but rather generalize them, so that the old (previous) theory becomes a particular case of the new theory. The new theory or parameterization contains a new parameter absent in the previous theory; when its value tends to some limiting value, the new theory transforms into the old theory. While the formulation of the correspondence principle is simple, it is nevertheless a very powerful methodological tool in understanding natural phenomena and developing correct generalizations of the existing theories and parameterizations. An important consequence of the correspondence principle is that a newer theory should be able to express the empirical parameters of the previous theories or parameterizations via the physical constants. The historical applications of the correspondence principle are beyond the scope of this book. Here, we emphasize that: When developing a new theory or parameterization, one should attempt to generalize previous theories and express the empirical parameters via physical quantities. A major goal of this book is to describe and develop further the theories that derive and generalize the known parameterizations of cloud microphysics, and to express the empirical parameters via the parameters of the theory and fundamental atmospheric constants. The correspondence principle provides an integrating framework for this book, and many examples of correspondence between the older and newer theories and parameterizations are described.

The theoretical approach taken in this book emphasizes solutions (primarily analytical) to limiting cases of the fundamental equations, that are then related to empirically derived relations that are applicable to specific conditions. The correspondence between the newly formulated theories and previous empirical relations is thus illuminated.

JC reflections

Here is some additional context/history regarding the book. In the 1980’s and 1990’s, clouds were the major focus of my research. My research used field data (primarily collected from aircraft), satellite data, and models. A major goal of my research during this period was to understand and model the the interactions between clouds and atmospheric circulations, with an objective of improving the treatment of clouds in weather and climate models.

In the mid 1990’s, I was becoming rather disillusioned the path I was on, since the time/space scales of clouds made them very difficult to observe and model. I felt that cloud parameterization had devolved into a big model tuning exercise. Since my Ph.D. thesis work circa 1980 on arctic clouds and radiation, I had been extensively reading the Russian literature, and I was aware that Russian cloud physics had evolved in a very different way from western cloud physics.

When I was approached by Vitaly Khvorostyanov to collaborate on modeling arctic stratus clouds, I jumped at the chance. I was intrigued by the Russian research on the kinetics of stochastic condensation, but didn’t really understand it – here was an opportunity to learn more about this.

Vitaly wanted to model clouds, whereas I was very intrigued by his theoretical approach to cloud microphysics. It seemed to me that significant progress could be made on the topic of cloud microphysics (in contrast to larger scale cloud processes). I was particularly impressed with his ability to interpret the structure of equations, make appropriate approximations, and solve the equations analyticallySince I was an upper level undergraduate, I had been enamored with numerical analysis, solving equations numerically (recall, these were the days when you needed to write code using Fortran, Mathematica was not available!) While in graduate school, I did take 4 applied maths classes, but continued to rely on numerical methods to solve equations. Because of the relative unavailability to scientists of computers in the Soviet Union in the 1970’s and 1980’s, atmospheric scientists in Russia relied much more heavily on analytical solutions to equations than did scientists in the West.

Our first collaborative papers were published in 1999, and we have jointly published 23 journal articles (I have been second author on all but one of these papers). The book synthesizes these articles in context of the correspondence principle, as well as introduces new research that has previously not been published.

This collaboration with Khvorostyanov has been the most satisfying one of my career. Apart from the obvious productivity in terms of journal articles and and now the book, I have learned an enormous amount from this collaboration. Most importantly, I feel as if I’ve contributed to something that is fundamental science (e.g. physics and physical chemistry), that I expect will stand the test of time (unlike the climate modeling exercise du jour) and hope will define theoretical cloud physics at the beginning of the 21st century.

One of the most challenging issues in climate change is the aerosol indirect effect (aerosol-cloud interactions); this book provides the intellectual underpinnings for developing physically based parameterizations of the processes that contribute to the aerosol indirect effect. So I hope that this book will be used widely by the atmospheric physics community, although I acknowledge that the extensive mathematics will deter some. With regards to the mathematics in the book, most of it is accessible to anyone who has taken an upper level undergraduate course in mathematical physics, i.e. I can follow and interpret the mathematics in the book (although I would be hard pressed to solve any of these equations myself).

I also hope that the mathematical/theoretical approach of this book will make it appealing to a broader audience of scientists and engineers (e.g. physicists, physical chemists, chemical engineers) and so introduce them to this fascinating and important topic.