The refractive index of atmospheric extracts sourced from urban (London), remote (Antarctica), and woodsmoke aerosol was determined by applying optical trapping simultaneously with Mie spectroscopy. In addition, owing to the absorbing nature of woodsmoke and an aqueous humic acid aerosol extract, the absorption Ångström exponent could be determined.The refractive index and absorption Ångström exponent were then applied in a top-of-the-atmosphere albedo radiation transfer model.