scope:

The dispersion category serves typically to characterise the whole mixing layer. It is also used as a characteristic variable for a larger horizontal spatial region. This means that it needs to be determined over a sufficiently long averaging period, in practice often one hour.

The dispersion category is quoted, for example, as a time series of successive hourly means, or in the form of a frequency distribution in which the individual situations are interpreted as stationary situations or as hourly means. Examples of time series and statistics and their formats can be found in VDI 3783 Part 21.

This standard uses the dispersion categories and designations listed in Table 1.