From AMS Glossary
- The relative mean molecular velocity of a selected gas undergoing diffusion in a gaseous atmosphere, commonly taken as a nitrogen (N2) atmosphere.
The diffusion velocity is a molecular phenomenon and depends upon the gaseous concentration as well as upon the pressure and temperature gradients present.
- The speed with which a turbulent diffusion process proceeds as evidenced by the motion of individual eddies.
Lettau, H. 1951. Compendium of Meteorology. 320–321.