Some problems concerning the terrestrial atmosphere above about the 100 km level

TLDR: In this article, it is shown that unless hydrogen atoms are being captured very rapidly from interplanetary space they must be very rare indeed at the base of the exosphere, and stress is laid on the importance of the steepness of the temperature gradient above the E layer in connexion with the thermal economy.

Abstract: Consideration is given to the significance of recent rocket and satellite studies relating to the structure of the thermosphere. It is shown that unless hydrogen atoms are being captured very rapidly from interplanetary space they must be very rare indeed at the base of the exosphere. Stress is laid on the importance of the steepness of the temperature gradient above the E layer in connexion with the thermal economy. Though no final conclusion is reached, it is thought that the view that the ionizing radiation from the sun is the main source of heat is more attractive than any alternative view yet put forward. An analytic model of the thermosphere is described in the appendix.