I view this book as having a "book within a book" involving the first six chapters. Those six chapters are essential for students studying dynamic meteorology, ranging from an introduction to the fundamental equations, to their simplification and application to understanding weather systems. I tried to restructure the book so that progression flows logically.
You can read about the details of the changes in the preface to the 5th edition, but here's a brief summary of the highlights for the first six chapters.
- In Chapter 1, there's a new section on kinematics, the analysis of motion without reference to forces. This material introduces basic aspects of the structure of wind systems, and defines quantities used to measure those aspects throughout the book, such as vorticity and divergence.
- Chapter 2 has new sections on the Boussinesq approximation and moist thermodynamics. These are used extensively later in the book, so I thought it made sense to elevate their status to the "basic conservation laws" chapter.
- In Chapter 4, potential vorticity is given a richer treatment, including a simple derivation from the Kelvin circulation theorem, and an introduction to tropopause maps, which provide a modern perspective for extratropical dynamics.
- Wave motions are vitally important in dynamic meteorology, so what was formerly Chapter 7 is now Chapter 5. Rossby waves, both stationary and propagating, are given expanded treatment, and the properties of these waves that distinguishes them from inertia-gravity waves are used to motivate the quasi-geostrophic equations that follow in Chapter 6.
- Chapter 6 has been mostly re-written from the 4th edition. The goal was to provide a streamlined, accessible, introduction to quasi-geostrophic theory. The basic elements of the theory are relatively simple, but it is easy to make QG theory seem very complicated and abstract. Two perspectives are given: "PV Thinking" and "W Thinking." PV Thinking provides a concise and powerful view of extratropical dynamics, but lacks a connection to vertical motion. W Thinking promotes the importance of vertical motion and the role of ageostrophic circulations in changing momentum, vorticity, and potential temperature. These concepts are illustrated with idealized disturbances modeled on archetypal weather disturbances found in midlatitudes (short-wave troughs and jet streaks). Moreover, MATLAB codes, including a QG model and diagnostic package, are provided for students to explore these ideas on their own. Students that master both perspectives have a powerful arsenal for explaining the existence of large-scale cloud patterns, and understanding the interaction of extratropical weather systems and their components.
