As one of the first steps in this study, all records of these phenomena reported in the logs of the Washington ARTC Center were tabulated. The tabulation, given as Table I of this report, was taken to the Analysis Section of the United States Weather Bureau where it was correlated with meteorological data for the periods involved. It was then discovered that a temperature inversion had been indicated in almost every instance when the unidentified radar targets or visual objects had been reported. Weather analysts were asked whether any unusual weather conditions had prevailed over the Washington area during the period covering the occurrences of large numbers of the unidentified radar targets. Their report may be condensed as follows:
The heat wave that broke records in the eastern portion of the United States during the month of Tune continued on through July, becoming intensified during the latter part of the month. July weather maps were characterized by a well-developed Bermuda high pressure area which remained in the vicinity of the southeastern coast line during the entire period. This high pressure area was responsible for an anticyclonic (clockwise) circulation of air over the eastern United States, a movement which continued during the month. This flow brought warm, moist air up from the Gulf of Mexico. The warm air mass usually extended up to about 10,000 feet. At higher levels the flow was from the west-southwest, and this continental air mass from the southwestern desert and drought area was hot and dry. Stagnation and heating of the air over the eastern United States was further increased because of an extremely strong band of westerly winds along the northern United States border, winds which prevented cold Canadian air masses from pushing south. Cyclonic activity was confined mostly to the area north of this band of westerly winds. There was a notable lack of thunderstorm activity in the Washington area. Physicists at the Naval Observatory reported that the amount of electrification in the air was very low.
The foregoing analysis indicated that the lack of cloud cover promoted solar heating in the daytime and rapid radiation cooling of the surface at night, This combination, with the prevailing light winds, was unusually conducive to the formation of temperature inversions during the hours of darkness.
Since the visual reports of flying saucers indicated that the observed lights spanned the same color range as the aurora borealis and since auroral effects closely follow sunspot activity, personnel of the Naval Observatory were consulted in order to determine whether any unusual sunspot activity had occurred during the period in question. They reported that there had been no unusual activity of this nature.
The Washington ARTC Center is the only one equipped with air route surveillance radar. However, several CAA control towers are equipped with airport surveillance radar, Type ASR-1. A survey of these locations produced the following results: