The Relation Connecting Skip Distance, Wavelength, and the Constants of the Ionized Layers

Neglecting the short-range ground ray, it is assumed that short-wave propagation is due to single or multiple total reflection between the earth and one or more ionized layers in the atmosphere. For single reflection at a single layer an equation is developed giving the wavelength in terms of the skip distance, the height of the layer and the degree of ionization of the layer. The curve represented by this equation is discussed. The equation, in conjunction with experimental data, shows the height of the layer which governs the skip distance in daylight to be about 230 km, and its ionization about 7.0×10⁵electrons per cu. cm. It is thought that, in daylight, higher layers of greater ionization do not exist. But there may be lower ones of lesser ionization. The theory is then applied to the case of multiple reflection in daylight. The data lead to a value of 10.4 meters for the shortest useful wavelength for daylight work. The case of two or more layers is next discussed, and experimental data for darkness are used, by means of the theory, to estimate the structure of the ionized regions at night. On winter nights there appear to be at least two layers, one at a height of about 520 km and with an ionization of about 2×10⁵electrons per cu. cm, the other at a height of the order of 40 km and with an ionization of the order of 3.5×10⁴electrons per cu. cm.