The 2013 Geophysical Fluid Dynamics Summer Study Program theme was Buoyancy-
Driven Flows. Professor Paul Linden of the University of Cambridge was the principal
lecturer. He ably introduced the topic from simple beginnings to sophisticated models and
observations, guiding the audience in the cottage and on the porch through fundamental
theory and applications. A number of topics from the lectures resurfaced in the fellows'
projects. The first ten chapters of this volume document these lectures, each prepared by
pairs of the summer's GFD fellows. Following the principal lecture notes are the written
reports of the fellows' own research projects.