Summary:Refractive index in the atmosphere depends mainly on temperature. Over ice or snow, because of the cold surface, the pattern of temperature variations will differ from that over normal surfaces. In an experiment on the Juneau Icefield, Alaska, air temperatures were measured in the lowest 12 m above the surface and reciprocal vertical angles were measured in the height range 15—70 m. Results from both types of observations were expressed in terms of the coefficient of refraction K. Remarkably high values for K are indicated, and there is an unexpected absence of the diurnal cycle in the variations.