Chapter 3 - Heat transfer

Abstract

This chapter describes the heat transfer processes in the Earth. Heat can be transferred by three processes: conduction, convection, and radiation. Conduction governs the thermal conditions in almost entire solid portions of the Earth and plays a very important role in the lithosphere. Convection dominates the thermal conditions in the zones where large quantities of fluids (molten rocks) exist, and thus governs the heat transport in the fluid outer core and the mantle. On a geological time scale, the mantle behaves as a viscous fluid due to the existence of high temperatures. Convection involves transfer of heat by the movement of mass, which is a more efficient means of heat transport in the Earth compared to pure conduction. In several processes of the Earth's interior, both conductive as well as convective heat transfer play important roles. Radiation is the least important mode of heat transport in the Earth. The process of heat exchange between the Sun and the Earth, through radiation, controls the temperatures at the Earth's surface. Inside the Earth, radiation is significant only in the hottest parts of the core and the lower mantle.