This course is an introduction to the fluid dynamics of the atmosphere and ocean, with an emphasis on dynamical concepts that explain the large-scale circulation of both fluids. Starting from the equations of motion, we will develop an understanding of geostrophic and hydrostatic balance, inertia-gravity waves, geostrophic adjustment, potential vorticity, quasi-geostrophic dynamics, Rossby waves, baroclinic instability, and Ekman layers.