Propagation of hydromagnetic waves in a rotating nonisothermal compressible atmosphere: WKB approximation

The propagation of internal Alfvén-inertio-acoustic-gravity waves in a rotating, stratified, inviscid, perfectly conducting nonisothermal atmosphere in the presence of a nonuniform magnetic field is investigated near the critical levels using the group velocity method based on the WKB approximation. It was found that these waves (approaching the critical level from one side) are neither transmitted nor reflected, but are completely captured in the neighborhood of the critical levels and are constrained thereafter to propagate in the horizontal directions. The same wave, if it approaches the critical level from the other side, is transmitted across the critical level without any absorption or reflection, thus establishing the valve effect, as in the case of Rudraiah and Venkatachalappa, even in the absence of the components of rotation in the plane normal to the direction in which the medium varies