I study how radiation, chemistry, and dynamics interact to determine the structure and variability of the atmosphere. In particular, I study the stratospheric circulation, which influences the thermodynamic state of the stratosphere and the distribution of trace constituents such as ozone and water vapor. The stratospheric circulation is driven by atmospheric waves originating in the troposphere, yet these tropospheric waves are not independent of the stratospheric state. For example, an increase in radiative heating in the stratosphere, e.g. due to volcanic aerosols, causes a thermal forcing that strengthens the stratospheric circulation via changes in wave propagation. Using observations, theory, and climate model simulations, I seek to clarify how various types of basic changes lead to associated changes in radiation, chemistry, and dynamics.