Disturbance waves are interfacial structures commonly found in the two-phase annular flow pattern with an essential role in mass, moment, and heat transfer. This work aims to broaden the knowledge on the behavior and characteristics of the disturbance waves and contribute to the literature on modeling approaches for vertical downward annular flows. The main features of those waves are investigated in a 26-mm ID, 14-m long pipe. The experimental campaign comprehends twenty-eight combinations of superficial gas and liquid velocities ranging from 5 m/s to 20 m/s and 0.05 m/s to 0.25 m/s, respectively. Air and water are used as working fluids. A non-intrusive, dual ring-shaped conductance sensor and an intrusive, capacitive 16×16 wire-mesh sensor arrangement are deployed in a test section placed at 335D from the flow inlet to measure temporal and spatial characteristics of the interfacial waves. The time signal analysis of the liquid film provides parameters such as velocity, frequency, amplitude, length and the onset of the disturbance waves. From the measurements with the wire-mesh sensor, a reconstruction of the interfacial structures was made to corroborate the disturbance wave evaluation regarding its circumferential profile.