A typical agricultural chemical spray process involves atomizing a liquid stream of diluted pesticide solution through hydraulic spray nozzles that inherently produce a wide spectrum of spray droplet sizes. Finer droplets have higher potential for off-target movement or drift, which is of concern due to its potential impact on neighboring crops and livestock, sensitive ecological resources, and human health. Research by the Spray Drift Task Force and others has demonstrated that, although spray nozzle selection and application parameters are the key factors to produce the desired droplet size spectrum, the physical properties of the spray solution have significant effects on the droplet size distribution for various kinds of nozzles. One of these properties of many spray fluids is the inclusion of an oil phase in the form of an emulsion. The effect of oil-in-water emulsions on the spray droplet size distribution has been demonstrated by previous work. However, the mechanisms of this effect are largely unknown. In this study, a method to model this effect was proposed. A characteristic dimensionless number for connecting the bulk spray properties and the microscopic emulsion droplet properties was defined as the ratio between the emulsion recovery time and the spray atomization time. This study will help in the design of agricultural spray nozzles and the optimization of anti-drift spray additives.