Recombination and electron attachment in the F layers of the ionosphere

Observational data for the ionosphere at Washington have been used as a basis for computations. The rate of recombination at night is roughly proportional to the square of the electron concentration, but the apparent recombination coefficient, a', tends to increase with decreasing electron concentration over the " half period of a sunspot cycle. This fact and the observed variation of a' with height indicate that electrons disappear both by recombination and by negativeion formation. The daily variation of electron concentration indicates that the F2 level is far above the level where the rate of production of electrons is a maximum in midsummer and that the FI layer is near the level where the rate is a maximum. It is assumed that both layers corne from the ionization of atomic oxygen.