Heat transport processes on planetary scales

This chapter evaluates mechanisms for heat transfer in large bodies, which include several processes that occur on scales and/or conditions that cannot be reproduced in the laboratory. Planetary interiors contrast with laboratory conditions by being layered, self-compressed spheroids, and moreover are open systems with internally graded gravitational acceleration, high temperatures, and high pressures. The large time- and length-scales of planets permit diffusion of visible radiation, even within their metallic cores. Advection of fluids coexisting with solids is very important in planets, due to fluid buoyancy, mobility, low viscosity, and their ability to carry latent heat and heat-producing elements: such behavior is covered in detail in this chapter. Theoretical problems in mantle convection models are reviewed, which include not conserving mass, and incorrectly representing the response of condensed matter to differential stress as the diffusion of momentum, rather than as elastic and plastic deformation.