view Abstract Citations (11) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Passage of Radiation Through Inhomogeneous, Moving Media. VII. - Cerning the Validity of the Geometrical Optics Approximation Lerche, I. Abstract We give the two coupled second-order differential equations that must be solved in order to obtain exact solutions for electromagnetic wave propagation in a plane differentially shearing medium of constant refractive index, n, and of velocity V = i V(y). For the simple case of normal incidence we demonstrate that the time-averaged power fiow is solely in the upstream direction at any point in the medium (for n < 1). The upgoing wave is balanced by a reflected wave from the critical height occurring at V(y) = cn < c. The upgoing ray path is shown to agree with the WKB (i.e., geometrical optics) ray path at high frequencies where the WKB analysis is expected to be valid. It is also pointed out that the instantaneous (not time averaged) power flow depends on the initial conditions and does not, in general, give rise to zero net power flow normal to the slab. Subject headings: hydromagnetics - radiative transfer Publication: The Astrophysical Journal Pub Date: August 1974 DOI: 10.1086/153021 Bibcode: 1974ApJ...191..763L full text sources ADS | Related Materials (14) Part 1: 1974ApJ...187..589L Part 2: 1974ApJ...187..597L Part 3: 1974ApJ...188..627L Part 4: 1974ApJ...191..191L Part 5: 1975ApJ...197..805L Part 6: 1974ApJ...191..753L Part 7: 1974ApJ...191..759L Part 9: 1974ApJ...194..165L Part 10: 1974ApJ...194..177L Part 11: 1974ApJ...194..403L Part 12: 1974ApJ...194..409L Part 13: 1975ApJ...198..477L Part 14: 1978ApJ...222.1020L Part 15: 1979ApJ...229..366L