This lecture covers the derivation of the vorticity equation in plane and spherical coordinates, emphasizing the importance of not confusing curved streamlines with vorticity. It also explores the advection-diffusion equation and solid body rotation, providing insights into the flow along a sphere and the application of Stokes formula. The presentation delves into the streamfunction formulation, the Biharmonic equation, and the rotational behavior in spherical coordinates, highlighting the significance of boundary conditions in the context of a sphere.