Densities and refractive indices of H₂SO₄/HNO₃/H₂O solutions to stratospheric temperatures

The Lorentz‐Lorenz relation is used to estimate the refractive index of aqueous H 2 SO 4 /HNO 3 solutions (5–70 wt%) for wavelengths from the near‐ultraviolet to the near‐infrared (0.35–2 µm) and for temperatures from 370 K to stratospheric temperatures (185 K). The molecular refractivities of the involved species are based on data of the binary solutions at room temperature. For the extrapolation to low temperatures, a careful estimate of the density of the ternary solutions has been performed. The accuracy of the model predictions is estimated to be better than 2%.