ABSTRACT
A general strategy is presented for the study of convection in a turbulent-fluid system, such as the Earth’s core, in which the adiabatic density differences across the system are much larger than the density differences that drive the convection. This situation is drastically different from the laboratory, where the density differences due to convection are the greater, and where the Boussinesq approximation is valid. The anelastic approximation deals satisfactorily with the large basic density differences across the system. Though the core is ‘an uncertain mixture of all the elements’, there seems to be little doubt that it is abundant in iron. There is general agreement that the fluid outer core is significantly less dense than iron would be at core pressures and that alloying elements must be present. Core turbulence presents the theory of core convection with its greatest challenge and students require the theory to be sufficiently simple so that it is integrated by computer.
