ABSTRACT
There is no complete theory of the dispersion of pollutants in the atmosphere. Instead, there are many theories, partly empirical and relatively little comprehensive data by which to choose. Nevertheless, there are many useful formulae, many of which give at least an insight into the problem. Modelling air pollutant dispersion is akin to weather meteorology and forecasting, and shares some of the uncertainties. The aim of this chapter is to explore our understanding of the atmosphere. It will refer briefly to air quality in terms of chemical composition, and hence its potential effects as a nuisance, on health, and on other aspects of environmental harm. In particular, the significance of how concentrations are expressed will be discussed in relation to aspects of statistical modelling. It will then consider its physical behaviour and define some of the input parameters needed to predict and model the transportation of pollutants. Inevitably, some theory is included. This is justified as the latest generation of dispersion models attempt to take account of the complex mathematics that describe variations of atmospheric behaviour with height.
