From the swirl of a wisp of smoke to eddies in rivers, and the huge persistent storm system that is the Great Spot on Jupiter, we see similar forms and patterns wherever there is flow - whether the movement of wind, water, sand, or flocks of birds. It is the complex dynamics of flow that structures our atmosphere, land, and oceans. Part of a trilogy of books exploring the science of patterns in nature by acclaimed science writer Philip Ball, this volume explores the elusive rules that govern flow - the science of chaotic behaviour.