We study in this paper the propagation of weak hydromagnetic waves in the exosphere between 1×103Km and 5×104Km height levels from the Earth's surface, based on simplified models. In the upper atmosphere the steady magnetic field is a dipole one, and it is, in general, difficult to discuss the wave propagation in such a field. But, in some special regions, an approximate treatment can be permitted. An attempt is made to describe two-dimensional wave fronts in the regions near the geomagnetic equatorial plane and high above the geomagnetic pole, using an approximate height-variation of the Alfvén wave velocity, and it is found that: (1) For our isotropic wave, the shape of wave fronts is the same for both the equatorial region and the polar one. (2) In the upper region above Va (Alfvén wave velocity) maximum height level the incident waves with large pitch angle to the zenith are almost reflected, and on the contrary, in the region below Va maximum height level the incident waves with any pitch angle have tendency propagating almost the Earth-ward.