Preliminary Data on the Optical Properties of Solid Ammonia and Scattering Parameters for Ammonia Cloud Particles

The infrared absorption spectrum of solid ammonia is obtained from 2 to 125 μm as a composite of the published measurements. From this, the absorption coefficient and the complex refractive index are calculated as a function of frequency by integration of the Kramers-Krönig dispersion relations. These data are used in a Mie theory analysis to obtain the basic parameters for scattering of long wavelength radiation by solid ammonia particles; this is believed to be an important process in radiative transfer within the atmospheres of the giant planets.