We consider the momentum effects on drop size and distributions during spray atomization. By adding the liquid and gas momentum analysis to conservation equations for mass and energy, we construct a formulation for determination of the spray drop size, number density, and liquid/gas velocities during spray atomization. In this approach, the aerodynamic drag is approximately parameterized by the drag coefficient, and viscous dissipation with dimensional scaling. This allows us to calculate the spray drop size and distributions from the injection parameters. The formulation also yields a broad dynamic perspective of spray atomization in which the liquid momentum undergoes deceleration due to drag and the drop size is the result of attendant energy transfer from the liquid kinetic to surface tension energy. Momentum adds a key component to the analysis of spray atomization leading to some useful relationships between the drop size and velocities. In this work, we present some methods for the use of momentum analyses for determination of drop size and distributions in various spray injection geometries.