diffusion

https://doi.org/10.1351/goldbook.D01716
The spreading or @[email protected] of a gaseous or liquid material. @[email protected] diffusion in the atmosphere is the process of transport of gases due to turbulent mixing in the presence of a composition @[email protected] Molecular diffusion is the net transport of molecules which results from their molecular motions alone in the absence of turbulent mixing; it occurs when the @[email protected] of a particular gas in a mixture differs from its equilibrium value. @[email protected] diffusion is the most important mixing process in the lower atmosphere, while molecular diffusion becomes significant at the lower pressures of the upper atmosphere.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2185 [Terms] [Paper]