The dependence of the nephelometer scattering coefficient of atmospheric air on the relative humidity at Research Triangle Park is discussed for four different meteorological examples. These examples feature (1) the passage of a low-pressure system with thunderstorms, (2) the passage of a cold, dry front, (3) a nocturnal weather disturbance due to an unknown source, and (4) wood-smoke aerosols from burning tree piles. Nephelometer scattering coefficient data were obtained using two nephelometers. One was operated at the ambient outside relative humidity and the other at a relative humidity inside an air conditioned building. Using this operational mode of data acquisition, qualitative temporal information can be deduced on the variations of aerosol size and number density as the various meteorological parameters vary. In addition to the variations of the aerosol physiochemical parameters, the temporal trend of the visibility for each example is discussed.