ABSTRACT
This chapter serves as a transition from consideration of integer to continuous random variables, which are useful for representing actual pollutant concentrations. It develops the Gaussian plume model from simple analogs. Diffusion is one of the most important processes that acts upon a pollutant released into the environment. In its simplest form, diffusion occurs when a molecule changes place with an adjacent molecule. Typically, the molecules of the pollutant released into a carrier medium change places with adjacent molecules of the carrier medium. As diffusion processes become more complex, they sometimes are called dispersion processes. The chapter discusses the distribution of particles with respect to space and time from a wedge machine. It illustrates that a particle frame machine gives results very similar to those predicted theoretically for the wedge machine by using the Gaussian plume model. The chapter also includes exercise problems related to diffusion and dispersion of pollutants.
