# Turbulent diffusion

From Glossary of Meteorology

## turbulent diffusion

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).

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