Previous studies of impinging jet atomizers indicated that "impact waves" may dominate the atomization of high-speed turbulent impinging jets. An experiment was conducted to characterize the formation and effects of impact waves on the atomization process. The model flow consisted of opposed turbulent water jets at atmospheric conditions. The impact waves are formed with a characteristic wavelength of about one jet diameter, and the distance between the waves was found to increase with distance from the impingement point due to wave merging, which helps explain discrepancies reported in the previous studies. A computational study of the flow structure around the stagnation point showed that the effects of impingement extend about one jet diameter upstream and that maximum gradients and incipient disruption of the surface occur at a normalized radius of 1.2, where an inflection in the jet flow from predominantly axial to predominantly radial occurs. Using these observations and measurements, and existing correlations for breakup length and drop size, a three-step phenomenological model of atomization (impact wave formation and propagation, sheet breakup into ligaments, and ligament disintegration into drops) was developed.