Deposition velocities are used in calculating deposition of nitrogen and sulphur. Different gases have different rates of deposition (and different deposition velocities) .
Deposition velocities are also different for different habitats. For example the rate of deposition of pollutants to forest vegetation is generally around twice that of deposition to short-vegetation. Forests and woodland habitats have a higher aerodynamic roughness (e.g. leaves, branches etc) as opposed to a more shorter type of vegetation habitat types.