Turbulent diffusion

From Glossary of Meteorology



turbulent diffusion

(Or eddy diffusion.) Diffusion or dispersion due to the effects of turbulent motions.

When quantifying turbulent diffusion, it is important to distinguish between two types of measurement: 1) single-particle diffusion, where we measure the distances between diffusing particles at a fixed point or a point moving with the mean fluid velocity, and where the mean-square particle displacement initially increases rapidly with time (e.g., linearly); and 2) two-particle diffusion, where we measure the distances between particle pairs or the dimensions of a cloud of diffusing particles. Here the mean-square distance initially increases more slowly (e.g., as the 5/ 2 power of the time).