Explore the third lecture in a series on geophysical fluid dynamics, focusing on balance, jets, and coherent structures. Delve into advanced concepts presented by David Dritschel as part of the Thematic Programme on "The Dynamics of Planetary-scale Fluid Flows" at the Erwin Schrödinger International Institute for Mathematics and Physics (ESI). Gain insights into complex fluid dynamics phenomena over the course of this 84-minute presentation, which contributes to a deeper understanding of planetary-scale fluid flows and their implications in geophysical systems.