Effects of Nuclear Explosions on the Ionosphere

Abstract

DURING October 30, 1961, some unusual phenomena occurred in the F-layer of the ionosphere over Lindau/Harz which may be ascribed to the explosion of the 50-megaton TNT nuclear bomb at 08 h. 33 m. 33 s. U.T. over Novaya Zemlya. Between the ½-hr. observations at 10 h. 00 m. and 10 h. 30 m. U.T. the critical frequency of the F2-layer increased by 3.7 Mc./s. This corresponds to an increase of the maximum electron density of more than 100 per cent. Afterwards the critical frequency dropped in an oscillatory manner showing up four maxima at intervals of approximately 1½ hr. each (Fig. 1). The ionograms during the period (Fig. 2), particularly at 11 h. 30 m. and 12 h. 30 m., exhibit very unusual features which cannot be explained by merely vertical reflexions. The critical frequency is so poorly defined on several of the ionograms that respective values have been omitted and replaced by the conventional letter S on the plot.