Figure shows the time variation of LWC at the top of the shaft; the shaded areas represent the periods of NaCl injection at the bottom. It is recognizable from the figure that the injection at the bottom induced distinct increase in LWC at the top after some delay. In Fig. is shown the droplet size distribution during the NaCl injection in comparison with that in the 'background' condition. The background was defined as the period prior to the NaCl injection, namely from 0 to 50 min on the horizontal axis of Fig. . Figure indicates that the size distribution had a peak around ∼ 7 µm (droplet diameter) in the background condition, while the distribution spread and the peak shifted toward larger size range during the NaCl injection. Therefore, the LWC increase shown in Fig. must be caused by the increase in large droplet size.