The dynamics of flows in density-stratified fluids has been and remains now an important topic for scientific enquiry. Such flows arise in many contexts, ranging from industrial settings to the oceanic and atmospheric environments. It is the latter topic which is the focus of this book. Both the ocean and atmosphere are characterised by the basic vertical density stratification, and this feature can affect the dynamics on all scales ranging from the micro-scale to the planetary scale. The aim of this book is to provide a “state-of-the-art” account of stratified flows as they are relevant to the ocean and atmosphere with a primary focus on meso-scale phenomena; that is, on phenomena whose time and space scales are such that the density stratification is a dominant effect, so that frictional and diffusive effects on the one hand and the effects of the earth’s rotation on the other hand can be regarded as of less importance. This in turn leads to an emphasis on internal waves.

High resolution direct numerical simulations are used to investigate the dynamics of turbulence in flows subject to strong stable stratification, which are common in natural settings. Results are presented for two categories of simulations, uniform and non-uniform density stratification. For all simulated flows, the density stratification was held constant in time, and there was no ambient shear. Flows with uniform density stratification are first analyzed to help provide clear insight to physical processes, followed by flows with non-uniform density stratification which better represent the stratification occurring in nature.

Stratified flows are important in determining how various atmospheric and environmental processes occur. The book investigates these processes and focuses on the methods by which pollutants are mixed and dispersed in natural and industrial environments.

The first papers of this conference addressed the long-standing issues of the nature of the upstream effects that occur in stratified flow over obstacles (P G Baines, CSIRO, Australia, A P Taylor, York University, Ontario, Canada; K W Ayotte, Boulder, Colorado, USA). Then followed a sessionon internal wave motions followed by a session on modelling the atmospheric boundary layer (J C King, British Antarctic Survey, Cambridge; A Kay, Loughborogh University of Technology). There was a session on numerical modelling (O Matais, Instite de Mecanique de Grenoble, France; A S Smedman,Uppsala University). The various aspects of dispersion were discussed and the final papers in the conference described laboratory experiments on flow and dispersion around buildings in light wind conditions.