The rather excessive public preoccupation of the immediate past with what has been labeled the 'environmental crisis' is now fortunately being replaced by a more sus tained and rational concern with pollution problems by public administrators, engineers, and scientists. It is to be expected that members of the engineering profes sion will in the future widely be called upon to design disposal systems for gaseous and liquid wastes which meet strict pollution control regulations and to advise on possible improvements to existing systems of this kind. The engineering decisions involved will have to be based on reasonably accurate quantitative predictions of the effects of pollutants introduced into the atmosphere, ocean, lakes and rivers. A key input for such calculations comes from the theory of turbulent diffusion, which enables the prediction of the concentrations in which pollutants may be found in the neighborhood of a release duct, such as a chimney or a sewage outfall. Indeed the role of diffusion theory in pollution prediction may be likened to the role of applied mechanics (,strength of materials') in the design of structures for adequate strength. At least a certain group of engineers will have to be proficient in applying this particular branch of science to practical problems. At present, training in the theory of turbulent diffusion is available only at the gra duate level and then only in a very few places.

The study of turbulence in the atmosphere has seen considerable progress in the last decade. To put it briefly: boundary-layer meteorology, the branch of atmospheric science that concentrates on turbulence in the lower atmosphere, has moved from the surface layer into the boundary layer itself. The progress has been made on all fronts: theoretical, numerical and observational. On the other hand, air pollution modeling has not seen such a rapid evolution. It has not benefited as much as it should have from the increasing knowledge in the field of atmospheric turbulence. Air pollution modeling is still in many ways based on observations and theories of the surface layer only. This book aims to bring the reader up to date on recent advances in boundary-layer meteorology and to pave the path for applications in air pollution dispersion problems. The text originates from the material presented during a short course on Atmospheric Turbulence and Air Pollution Modeling held in The Hague during September 1981. This course was sponsored and organized by the Royal Netherlands Meteorological Institute, xi xii PREFACE to which both editors are affiliated. The Netherlands Government Ministry of Health and Environmental Protection and the Council of Europe also gave support.

The rather excessive public preoccupation of the immediate past with what has been labeled the 'environmental crisis' is now fortunately being replaced by a more sus tained and rational concern with pollution problems by public administrators, engineers, and scientists. It is to be expected that members of the engineering profes sion will in the future widely be called upon to design disposal systems for gaseous and liquid wastes which meet strict pollution control regulations and to advise on possible improvements to existing systems of this kind. The engineering decisions involved will have to be based on reasonably accurate quantitative predictions of the effects of pollutants introduced into the atmosphere, ocean, lakes and rivers. A key input for such calculations comes from the theory of turbulent diffusion, which enables the prediction of the concentrations in which pollutants may be found in the neighborhood of a release duct, such as a chimney or a sewage outfall. Indeed the role of diffusion theory in pollution prediction may be likened to the role of applied mechanics (,strength of materials') in the design of structures for adequate strength. At least a certain group of engineers will have to be proficient in applying this particular branch of science to practical problems. At present, training in the theory of turbulent diffusion is available only at the gra duate level and then only in a very few places.

This publication of the AMS contains all the lectures that were presented at the AMS Workshop on Meteorology and Environmental Assessment held in Boston, MA on September 29-October 3, 1975. Topics include: The dispersion of materials in the atmospheric boundary layer, atmospheric dispersion models for environmental pollution applications, plume rise predictions, turbulent diffusion and pollutant transport in shoreline environments, urban diffusion problems, atmospheric transformations of pollutants, observational systems and techniques in air pollution meteorology, and federal government requirements for environmental impact assessment.

Since its discovery in early 1900, turbulence has been an interesting and complex area of study. Written by international experts, Air Pollution and Turbulence: Modeling and Applications presents advanced techniques for modeling turbulence, with a special focus on air pollution applications, including pollutant dispersion and inverse problems. The

Finishing this book is giving me a mixture of relief, satisfaction and frus tration. Relief, for the completion of a project that has taken too many of my evenings and weekends and that, in the last several months, has become almost an obsession. Satisfaction, for the optimistic feeling that this book, in spite of its many shortcomings and imbalances, will be of some help to the air pollution scientific community. Frustration, for the impossibility of incorporating newly available material that would require another major review of several key chap ters - an effort that is currently beyond my energies but not beyond my desires. The first canovaccio of this book came out in 1980 when I was invited by Computational Mechanics in the United Kingdom to give my first Air Pollution Modeling course. The course material, in the form of transparencies, expanded, year after year, thus providing a growing working basis. In 1985, the ECC Joint Research Center in Ispra, Italy, asked me to prepare a critical survey of mathe matical models of atmospheric pollution, transport and deposition. This support gave me the opportunity to prepare a sort of "first draft" of the book, which I expanded in the following years.

What do the movements of molecules and the migration of humans have in common? How does the functionality of our brain tissue resemble the flow of traffic in New York City? How can understanding the spread of ideas, rumors, and languages help us tackle the spread a pandemic? This book provides an illuminating look into these seemingly disparate topics by exploring and expertly communicating the fundamental laws that govern the spreading and diffusion of objects. A collection of leading scientists in disciplines as diverse as epidemiology, linguistics, mathematics, and physics discuss various spreading phenomena relevant to their own fields, revealing astonishing similarities and correlations between the objects of study—be they people, particles, or pandemics. This updated and expanded second edition of an award-winning book introduces timely coverage of a subject with the greatest societal impact in recent memory—the global fight against COVID-19. Winner of the 2019 Literature Prize of the German Chemical Industry Fund and brainchild of the international and long-running Diffusion Fundamentals conference series, this book targets an interdisciplinary readership, featuring an introductory chapter that sets the stage for the topics discussed throughout. Each chapter provides ample opportunity to whet the appetite of those readers seeking a more in-depth treatment, making the book also useful as supplementary reading in appropriate courses dealing with complex systems, mass transfer, and network theory.