Atmospheric aerosols were intensively studied in Tainan in southern Taiwan from February to March 1995. The time-series data showed that variations of hourly aerosol light-scattering coefficients (σ(scat)) and aerosol volume concentrations were consistent with a squared correlation coefficient at 0.87. For comparisons with the measured σ(scat), the aerosol light-scattering coefficient was calculated (σ(scat, c)) using the Mie theory and aerosol size spectra. A linear regression analysis showed that the squared correlation coefficient between σ(scat, c) and σ(scat) was at 0.89. During the study period, certain events were observed which might result from variations of either meteorology or source emissions. The morning fog was found to have the most progressive growth in the range of 0.8 to 0.9 μm, with a minor contribution from a size interval of 1 to 2 μm. In contrast, other activities showed the most progressive size interval was from 0.35 to 0.6 μm. In this study, two cases affected predominantly by the variations in relative humidity (RH) were chosen to investigate the σ(scat, c) across aerosol sizes. In an ascending RH environment, the σ(scat) increased from 0.35 to 0.50 km-1 with an increasing σ(scat, c) in the range from 0.2 to 0.9 μm. For a descending RH environment, the σ(scat) reduced from 0.75 to 0.14 km-1 with a significant reduction in σ(scat, c) for the range from 0.45 to 2.0 μm.