Yale geology and geophysics professor Ron Smith continues his course Atmosphere, the Ocean and Environmental Change with a lecture on how pressure and density fall off exponentially with altitude, producing the buoyancy effects behind rising and sinking air parcels. He traces temperature's more irregular path through the atmosphere, pointing out the inversions that mark the boundaries between layers, and explains how each layer's gas composition filters which wavelengths of solar radiation reach the surface. The lecture then extends the same layered-structure thinking to the ocean and the Earth's interior before shifting to systems analysis and the concept of residence time, worked through with the hydrologic cycle as the running example. Chapter markers break the fifty-minute talk into density and pressure structure, temperature structure, radiation interaction, height-scale examples, oceanic and geologic layering, and the closing systems discussion. Recorded at Yale in Fall 2011 as part of Open Yale Courses.