Waves in the Solar Atmosphere

other effects of the magnetic field, although we know quite well that in the plage areas, and probably in the chromosphere, this is a very crude assump­ tion. We shall also disreg ard the dynam ics of convective zones, because for the Sun this is not properly an atmospheric problem. As far as the Sun is con­ cerned, we shall restrict our discussion to a rather thin layer, the high photo­ sphere and the low chromosphere. The relevance of such a restricted study to astrophysics is twofold: first, the dynamics of atmo sphe res free from mag­ netic fields presents such a varie ty of physical problems, some of which have not been studied, that it is wort h while to discuss the work that has been done in the field and to situ ate the yet-t o-be-discove red areas with respect to the