4) Since the ground radar stopped functioning at this point, the operator could no longer track the course of the unknown or of the interceptors. If the radar had been working, he would have seen that the target continued on to the southwest while the interceptors were searching in a different area to the north. 5) The photographs confirmed this reconstruction of a complicated series of events. The pictures obtained by the gun camera displayed a round, indistinct blur. Analysis showed that the size of the object was that of a twenty-foot sphere--a balloon--photographed from a distance of 30,000 feet. _“Ghosts” and “Angels” on Radar_ Every experienced radar man has observed blips on his scope that he cannot account for[VIII-4], but he recognizes many characteristics of these “ghosts” or “angels.” They often come from an apparently clear and normal sky. They are usually concentrated in the lower atmosphere, are weak in character, and last only a short time. Although they may occur at any time of the year, they appear most often on summer nights in calm weather[VIII-10]. Summer atmospheric conditions, in which the air is relatively quiet but varies in temperature and moisture content, have an adverse effect on radio and radar transmission and produce many of these ghost returns. The uneven distribution of temperature and humidity in the atmosphere is only one of the many possible causes of the radar angels often labeled as saucers[VIII-11, VIII-12]. These ghosts may be produced by peculiar atmospheric conditions, back and forward scatter of radio waves[VIII-13], smoke, wind-carried debris, moisture-laden clouds, ice crystals in clouds or air, lightning, meteors, the Aurora Borealis, birds, insects, bats, electronic reflections from the moon, flares on the sun, or by “chaff” or “window” (foil dropped from airplanes). A radar operator once picked up a group of phantom echoes that seemed to form the letters “GI” which, according to the scope, apparently stretched over a distance of about eighty miles. He tracked them for two hours, but gave up trying to interpret the message when he learned that it was produced by chaff dropped from an Air Force plane during an experiment. An extremely unusual pattern of “angels” (see Plate IVc) appeared on the radarscope at Schilling Air Force Base at Salina, Kansas, on September 10, 1956, and was attributed to forward scatter from atmospheric eddies to ground targets and back[VIII-13].