Adding 20 ¿m spectral observations to observations in the 8--12 ¿m region can significantly improve infrared cloud phase determination from both space and the surface. We demonstrate this with 7--20 ¿m radiance spectra of Arctic stratus clouds measured by a ship-based FTIR spectrometer during the SHEBA experiment. Our results are compared with phase classifications obtained from lidar, microwave radiometer, and radar data.