The processes of sulfur dioxide dissolution into cloud droplets and its successive oxidation to sulfate were studied in a real scale cloud facility prepared in a vertical shaft of a mine. Sulfur compounds in droplets, aerosols and gas were collected by serial samplers, a droplet impactor, a teflon filter for aerosol particles and a Na2CO3-impregnated filters for SO2 gas. Samplers are installed at several height including the bottom, a level below the cloud base, and levels in the cloud. Sampling by an autosampler loaded on an elevator which goes up and down in the vertical shaft was also carried out. The concentrations of sulfur compounds at each height indicates that the released SO2 at the bottom of the shaft was absorbed by cloud droplets but the oxidation rate of sulfite to sulfate was slow. It may be due to the absence of light in the shaft which produces oxidation reagents such as ozone and so on.
