THE APPLICABILITY OF CONTINUOUS-FLUID THEORY IN THE HIGHER ATMOSPHERE

Abstract

The validity of the concept of winds in the higher atmosphere is associated with the physical restrictions governing the selection of the infinitesimal volume, or mass element, used in the development of the equations of motion. Numerical criteria concerning the size of the mass element are presented and applied to the higher atmosphere. A modification of the equations of motion, to include higher-order pressure derivatives, appears necessary in the F region. Consideration must be given to the special interpretation of the variables in such equations. An evaluation of pressure in an isothermal atmosphere suggests that the density decreases less rapidly with height above the F region than in the standard equation. The results of the study imply an increased confidence in the use of conventional equations in the E region and show a need for further study of basic relations in the F region.