A model of the ionosphere

Observations and theories of a number of geophysical phenomena associated with the ionosphere are summarized. A proposed model of the ionosphere seems to provide qualitative interpretations of most of these phenomena. In low and intermediate latitudes electrons are assumed to rise; they migrate through the upper ionosphere to the polar region, where they fall and complete the circuit through the ground. Under the action of an electric field, positive ions, which are formed at great heights by ultraviolet light, tend to rise, whereas negative ions descend. Since the ions are constrained to helical paths along the sloping magnetic lines of force, positive ions tend to collect in a ring near the plane of the geomagnetic equator; negative ions accumulate in the polar regions. Solar radiation‐pressure distorts the ion‐ring and blows the tail to a height of several Earth‐radii. Electric discharges between the positive ion‐ring and the negative polar caps produce magnetic disturbances and the associated auroral displays.