‘Ring Angels’ over South-East England

Abstract

IN the course of observations on radar ‘angels’ which we have been making during the past two years, we have occasionally noted formations of angels which are clearly related to the ring angels reported by Elder¹ at Ypsilanti (U.S.A.) in 1957. Fig. 1 shows a typical and fully developed ring angel which was observed on February 17, 1959. This record was obtained with a high-power L-band radar of conventional design; the signals were displayed on an ordinary plan position indicator with video map superimposed on the radar signals. The antenna was rotated at four revolutions per minute and the displays were photographed on each scan. If a film secured in this way is exhibited through an ordinary ciné projector running at sixteen frames per second, an acceleration of 240 times is obtained, and in these circumstances the dynamic growth of the ring angel can be clearly observed. The ring angel commences as a strong point echo; it then extends into an annular ring, to be followed by other rings at approximately equal intervals of time. The whole phenomenon has precisely the same appearance as the ripples on a pond expanding from a point of disturbance. In the case of the rings shown on Fig. 1, eighteen rings were emitted from the centre with an average periodicity of 2½ min. and a maximum diameter of 20 miles was achieved.