The dynamics of flows in density-stratified fluids are an important topic for scientific enquiry. Flows arise in many contexts, ranging from industrial settings to the oceanic and atmospheric environments. Both the ocean and atmosphere are characterized 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. This volume provides 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, 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, can be regarded as of less importance.