Some physical aspects of the ionosphere

The paper surveys the current state of knowledge of the properties of the ionosphere, in particular those which have become more important or more accurately known through the use of sounding rockets and artificial Earth satellites. The atmosphere and its electrical propertiesare first discussed. An account of wave-electron interaction and incoherent scattering from electrons is followed by consideration of the roperties of the D, E and F regions, and finally scatter propagation is briefly discussed.