Dynamics of the Atmospheres of the Major Planets with an Appendix on the Viscous Boundary Layer at the Rigid Bounding Surface of an Electrically-Conducting Rotating Fluid in the Presence of a Magnetic Field

Abstract

The interpretation in terms of basic hydrodynamical Processes of certain prominent observational features exhibited by the atmospheres of major planets should lead in due course to accurate information about the internal structure of these bodies (e.g. atmospheric depth, angular momentum transfer, energy sources) that may be obtainable in no other way. Tentative information of this kind has already been found as a result of attempts to interpret 1) the Great Red Spot and other, less persistent and generally smaller, spots on Jupiter's visible surface, 2) the banded appearance, and complicated and striking variation of rotation rate with latitude, including the equatorial jets, of Jupiter and Saturn, and 3) Jupiter's magnetic field, with its characteristic rotation period. The dynamical influence of rotation on relative motions in the atmospheres of the major planets is much more pronounced than in the case of the earth's atmosphere, though effects due to vertical density stratification are probably much less important. Possible complications arise because 1) the major planets rotate hypersonically with respect to the speed of sound in their atmospheres, and 2) the electrical conductivity of the lower reaches of these atmospheres might be sufficiently large for magnetohydrodynamic processes to occur there. If, as has been suggested, these processes produce, or at least modify, Jupiter's magnetic field, then future research on the dynamics of the atmospheres of the major planets should include attempts to detect the magnetic fields of Saturn, Uranus and Neptune, and to determine the configuration of the magnetic field in the vicinity of the visible surface of Jupiter, carried out in conjunction with attempts to measure the electrical properties of the outer layers of the planets and systematic theoretical studies of the hydrodynamics and magnetohydrodynamics of hypersonically rotating fluids. The paper ends with an Appendix on the theory of the structure of the viscous boundary layer at the rigid bounding surface of an electrically-conducting rotating fluid in the presence of a magnetic field.