Radiative transfer ia the Earth's mantle

Abstract

The equation governing the transfer of heat in non‐opaque media is derived and reduced to a form suitable for calculation. The optical absorption coefficients of minerals are estimated to be 10 cm −1 to 30 cm −1 under surface conditions, but they rise to much higher values a t high temperatures because of an increase of electrical conductivity with temperature. Hence radiative transfer will be most effective in the outermost 600 km of the Earth; at these depths the effective thermal conductivity may be considerably increased by radiative transfer. The presence of an outermost shell having a high conductivity may increase the heat lost from the Earth in geologic time by a factor of two over previous estimates.