Lecture notes on Chapter 13: The Generation of Eddies by Instability. Topics include instability, buoyant convection, Rayleigh?Benard instability, convective adjustment and gravity wave breaking, reversal of mesopause temperature gradient, Kelvin-Helmholtz instability, radiating and growing solutions, instability of meteorological disturbances, baroclinic and barotropic instability, the Kelvin-Orr mechanism, two-level baroclinic model, baroclinic instability and climate, geometric stabilization, energetics of meteorological disturbances, and available potential energy.