# Eddy diffusion

Because the microscopic processes responsible for atmospheric mixing are too complex to model in detail, atmospheric modelers generally treat atmospheric mixing as a macroscopic "eddy" diffusion process. In this approach, the diffusion rate at each pressure level is parameterized by a quantity known as the eddy diffusion coefficient, K[4] (also sometimes called eddy diffusivity, with units of $m^2 s^{-1}$).