Theory of the ionosphere

Introduction —During the past ten years the ionization in the reaches of the atmosphere at several hundred kilometers above sea‐level has been explored by means of radio waves. Concurrently with the experimental investigations various possible causes of the ionization have been examined from the theoretical standpoint and this in turn has called for theoretical elaboration of the entire physics of the high atmosphere. The recent and detailed ionosphere‐measurements of the National Bureau of Standards and of the Department of Terrestrial Magnetism of the Carnegie Institution of Washington permit a closer scrutiny of fact and theory than has been possible heretofore. In the following brief resume a few of the more important conclusions are outlined.