Ionization, negative‐ion formation, and recombination in the ionosphere

Abstract

The ionization in the ionosphere is discussed in the light of present theories of recombination and negative‐ion formation. It is suggested that the E ‐ and F 1 ‐regions are formed as the result of the absorption of special bands of solar radiation and that negative‐ion formation is the predominant process in these regions. A sufficient number of electrons exists, however, to cause the reflection of electromagnetic waves. The F 2 ‐region is probably not due to the absorption of any special band of solar radiation but owes its formation to the preponderance at this elevation of electron‐positive‐ion recombination over negative‐ion formation during the day. The characteristics of the E ‐ and F 1 ‐regions are discussed quantitatively and compared with experimental observations. A qualitative discussion is given for the F 2 ‐region since it seems probable that significant changes in level and density take place at these elevations.