On the nature of traveling ionospheric disturbances launched by low-altitude nuclear explosions

The nuclear explosion of October 30, 1961, over Novaya Zemlya, resulted in major perturbations of the F-layer critical frequency, even at very great ranges from the explosion site. These perturbations have been interpreted in terms of long-period gravity waves, and more recently in terms of shorter-period acoustic-gravity waves. It is shown here that the new interpretation is unsatisfactory, while the old is perfectly consistent with the observations if allowance is made for the obliquity of energy propagation. The results have some bearing on natural traveling ionospheric disturbances as well.