The framework for a simulation model is presented which describes the dispersion of individual droplets of water containing viable microbes. The model accounts for physical, chemical, biological and measured meteorological parameters of each droplet at each of many short time steps. Repeating the modelling process for many droplets will simulate a cloud of droplets. The model is compared with the Tulelake, CA release in 1988, and revealed very similar patterns of deposition within 30 m (the maximum observation distance of the source). A hypothesis for the survival sequence in the microbe-containing droplets is discussed.