Solar radiation in the far infrared (wavelengths 200-10000 arises primarily from the region of the solar atmosphere near the temperature minimum in the low chromosphere (Ref. 1). An accurate specification of the temperature structure of this region of the sun is important for an understanding of the processes of nonradiative energy transport since it is here that departures from radiative equilibrium first become important in the chromosphere. Because of the relatively high opacity of this region, a comparatively large input of energy is required to support a temperature structure here only slightly above the radiative equilibrium value (Ref. 2).