Atomization of a liquid jet in a convergent-divergent gas nozzle is studied both theoretically and experimentally. The jet enters the nozzle through a central tube and is primarily disintegrated in the vicinity of the tube exit. An integral model allows cumbersome calculations to be avoided. The model uses idealized schemes for the coarsely and finely dispersed mixture after primary and secondary atomization, respectively. Comparison of theoretical results with experimental data demonstrates the applicability of the model for prediction of the atomizer's geometry and operating conditions necessary for producing the finest possible mixture.