Case 1

South Mountain

Spring 1950

Investigators: Low, staff

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A professional meteorologist saw an unidentified object flying beneath clouds. He believed the object to be a powered craft three to five feet in diameter. Positive identification cannot be made, although the possibility that the object was common earth debris is suggested.


A UFO sighting from the grounds of an Observatory had attracted attention because the observation was made by a professional meteorologist who is highly regarded in the scientific community. The meteorologist wrote the following account within an hour of his observation:

I saw the object between 12:15 and 12:20 p.m. ............from the grounds of the........Observatory. It was moving from the Southeast to the Northwest. It was extremely prominent and showed some size to the naked eye, that is, it was not merely a pinpoint. During the last half of its visibility I observed it with 4-power binoculars. At first it looked like a parachute tipped at an angle to the vertical, but this same effect could have been produced by a sphere partly illuminated by the sun and partly shadowed, or by a disc-shaped object as well. Probably there are still other configurations which would give the same impression under proper inclination and


illumination. I could see it well enough to be sure it was not an airplane (no propeller or wings were apparent) nor a bird. I saw no evidence of exhaust gases nor any markings on the object.

Most fortunately the object passed between me and a small bright cumulus cloud in the Northwest. Thus it must have been at or below the cloud level. A few seconds later it disappeared, apparently into the cloud.

Against the sky it was very bright but against the cloud it was dark. This could be produced by a grey body which would be bright against the relatively dark sky, but dark against the bright cloud. Alternatively, if the object were half in sunlight and half shadowed the sunlit part might have had no detectable contrast with the cloud while the shadowed part appeared dark.

I immediately telephoned the U.S. Weather Bureau (2-3 miles S.W. of the Observatory). They were estimating the cloud to be 6000 feet above the ground. Now estimates of cloud heights are rather risky, so I obtained their observations of temperature and dew point, and from the known lapse rates of these quantities in a convective atmosphere, calculated the cloud base to be at 12,000 feet. I believe this latter figure to be the more accurate one because later in the afternoon the cumulus clouds thickened but at all times remained well above the tops of our nearby mountains. These are about 6000 feet above us.

Thus, having some idea of the object's elevation and its angular diameter through the binoculars (about equivalent to a dime seen at


50 feet with the naked eye), I calculated its size to be 3 to 5 feet for a height of 6 - 12 thousand feet, and a zenith angle of about 45o. This size estimate could easily be in error by a factor or two, but I am sure it was a small object.

The clouds were drifting from the SW to the NE at right angles to the motion of the object. Therefore, it must have been powered in some way. I did not time it but for that elevation I would estimate its speed to be about 100 miles per hour, perhaps as high as 200 m.p.h. This too means a powered craft. However, I could hear no engine noise.


The meteorologist who reported this observation was interviewed. He could offer no information beyond his original report written 17 years earlier. In earlier correspondence with project personnel, however, he furnished copies of letters exchanged in 1961 with another interested scientist who suggested alternate explanations of his observation.

The crucial point in question was the height of the object, coupled with the direction of wind at that elevation. Did the object disappear into a cloud, thus showing it to be at cloud level, or was its abrupt disappearance due to reorientation of the object relative to the observer, such as the turning of a sheet of paper edgewise to the observer, or to passage of a reflecting object into the shadow of a cloud? In either of the latter cases, the observed object could have been much lower than cloud level in which case its motion could be accounted for by winds, and the requirement of self-propulsion would no longer pertain.


Loren W. Crow, Certified Consulting Meteorologist, was commissioned to analyze records of weather pertinent to this observation. He studied surface weather records, and winds aloft data from this South Mountain area. According to his report, winds were light and variable at all stations. He presented a vertical profile of cloudiness and the following evidence of strong vertical mixing. (Crow's Fig 4 is not included in this excerpt from his report).

Excerpts have been made from the detailed surface observations at three stations. It is worth noting that at approximately 12:30 (the observations actually being made prior to this filing time)... [two stations] carried a notation under remarks that dust devils were being observed. From the Glossary of Meteorology a dust devil is defined as a well-developed dust whirl. The following is a further quotation from that definition.

...A rapidly rotating column of air over a dry and dusty or sandy area, carrying dust, leaves and other light material picked up from the ground. When well developed it is known as a dust devil. Dust whirls form, typically, as the result of strong convection during sunny, hot, calm summer afternoons. This type is generally several yards in diameter at the base, narrowing for a short distance upward and then expanding again, like two cones ape to apex. Their height varies; normally it is only 100 to 300 feet, but in hot desert country they may be as high as 2000 feet...


The actual lowering of temperature between 12:30 and 13:30 at... [airport A] indicates that strong vertical mixing took place during that hour. It could have started in the vicinity of ... [city A], particularly over the warmer portions of local heat absorbing surfaces, a few minutes or an hour earlier.

The spread between dry bulb and wet bulb temperature was comparable at each of the three stations, indicating that they were in the same air mass. This spread was slightly less at the ... [airport A] than at...[city B or C]. Super-adiabatic temperature lapse rates would have been prevalent near the surface in the late morning hours.

Surface conditions were quite dry. The most recent rainfall above a trace recorded at both... [city A and airport A] occurred on May 4, sixteen days earlier. The amounts received at that time were .34 inch in... [city A] and .35 inch at the airport [A]. The maxima temperatures were well above normal for the month on May 20. The maximum of 830 at ... [city C] was the first such maximum that had been reached in 1950. A warmer maximum temperature had been recorded on only one day previously at... [city A].

The vertical wind profiles show only light winds prevailing at the level of the sighting. The direction of air flow at the sighting level as indicated by the pressure pattern would have been from the northeast. Velocity would have


been less than 10 mph and could have been overcome by local convective activity or the influence of any particularly large cloud development.

It is the author's opinion that within the hour prior to the sighting strong vertical mixing of the air in the first 3,000 feet above the surface would have been a typical pattern of air motion in the vicinity of the sighting. Horizontal flow of air would have been limited to velocities not exceeding 10 mph. Visibility would have been excellent.

In addition to his report, Crow expressed the opinion that some light, low density material must have been carried aloft by a localized dust whirl not too far from the observer. He suggested that at the time of sighting vertical motion no longer was being applied and the object was drifting slowly along a nearly horizontal path from NE toward NW. Although the witness reported cloud movement, Crow suggests that this observation could have been the result of movement of the object combined with very slight cloud movement, producing the impression that the cloud was drifting more than it actually was. A near-deflated child's balloon or a sheet of paper, carbon paper, or plastic at an altitude of 1500-3000 ft. could have caused observations similar to those reported.


There is no way to establish the altitude of the reported object. It is not certain that the object was at cloud elevation, for there are other acceptable explanations of abrupt disappearance of such an object. Thus, the object may have been much nearer to the observer than he assumed, and may have been airborne debris.