Recent Studies of the Ionosphere

Results of ionosphere measurements utilizing transmissions at vertical incidence and made weekly over a period of eighteen months are discussed. Typical graphs of diurnal variations of the E-layer critical frequency and its relation to the ionizing force of the sun are shown for three seasons. Similar graphs for the F2layer are included as well as a seasonal curve of midday, and maximum critical frequencies of this layer. The absence of midday F2critical frequencies during the summer is pronounced. A sporadic E layer appearing at the same virtual height as the normal E, and after the normal E has reached its critical penetration frequency, is discussed. A comparison of its appearance with local thunderstorms, is tabulated. The presence of a tentatively named G layer is indicated.