"It follows from this that the radiation from the earth into space does not go on directly from the ground, but on the average from a layer of the atmosphere having a considerable height above sea-level. The height of that layer depends on the thermal quality of the atmosphere, and will vary with that quality. The greater is the absorbing powerof the air for heat rays emitted from the ground, the higher will that layer be. But the higher the layer, the lower is its temperature relatively to that of the ground; and as radiation from the layer into space is the less the lower its temperature is, it follows that the ground will be hotter the higher the radiating layer is."
By Nils Ekholm, April 1900 in a paper "On variations of the climate of the geological and historical past and their causes" (Vol. XXVII -1901 Quarterly Journal of the Royal Meteorlogical Journal)