Interplanetary space and the earth’s outermost atmosphere

Abstract

The static temperature distribution T(r) in the solar corona is discussed theoretically on the basis of alternative idealized assumptions as to its state-—in particular, for thermal conductive equilibrium and for turbulent adiabatic equilibrium . Up to a distance of 20 solar radii, T(r) is inferred from the electron density data given by Blackwell and others. It is concluded that T(r) lies between the conductive and adiabatic distributions. The influence of the rotation of the gas is considered; it does not much affect the inferred T(r) up to 20 solar radii, b u t ignorance of the rotation a t greater distances a t present precludes an estimate of the coronal electron density a t the earth’s distance. The coronal temperature extrapolated to this distance is judged to be of order 100000 °K— a high value, though less than that formerly estimated on the basis of thermal conductive equilibrium . The influence of the hot coronal gas on the earth’s outermost atmosphere is discussed, including the conductive h eat flow therefrom into our atmosphere.