Abstract
We are interested in the manner of propagation of hydromagnetic waves in the Earth's upper atmosphere. The density changes continuously in the atmosphere and the steady magnetic field is a dipole field, but we discuss here the laws of reflection and refraction of hydromagnetic waves at a plane boundary between two semi-infinite homogeneous media of anisotropic electrical conductivity under a uniform steady magnetic field. When the steady magnetic field is perpendicular to the boundary plane, the laws of reflection and refraction are simple, but when the steady magnetic field makes an angle with the plane, they are complicated. The incident ordinary (or extraordinary) waves may be reflected or refracted as the ordinary or extraordinary waves and propagate anisotropically.
