Project Blue Book case file: Kenneth Arnold

Read from the scan by GLM-OCR; expect the odd misread word.

atmosphere when stable currents of air now over obstacles hills or mountains. An up-and-down wave motion may be impressed upon the air, provided that temperature and wind conditions are suitable. As the air describes its wavelike path, it alternately warms and cools, the warming taking place as it sinks into the wave trough and the cooling as it ascends to the wave crest. If the air is very dry, the undulating current will not be visible to the eye, although the updrafts and downdrafts will readily be felt by aircraft that chance to pass through them. On the other hand, if the air before entering the wave is moist enough, the cooling in the wave crest will cause water droplets to condense and a cloud to appear.

In the vicinity of an isolated peak the cloud may assume the form of a cap covering the summit, or it may be displaced slightly downwind and resemble a lens or disk. Not infrequently a series of lenticular clouds will appear, trailing downwind at regular intervals of a few miles. Although these wave clouds are usually stationary, they sometimes move at great speed, especially when the air temperature is changing rapidly.

From a study of a remarkable photograph made in 1956, R. J. Reed of the University of Washington has offered striking evidence that the disks saw were actually wave clouds in rapid motion.

On the afternoon of December 29, 1956, a photographer for the Seattle Times was on top of Pigtail Peak near White Pass, Washington (not far from the area where Arnold's nine disks had appeared), taking ski pictures for the rotogravure section of the Sunday Times. The weather was beautiful. Down in the pass temperatures hovered near freezing, but the slopes were warmed by sunlight that filtered down through thin cirrus clouds and raised the temperature to a balmy fifty degrees. Just at sunset a strange object suddenly appeared off toward the northeast horizon. Several skiers urged the photographer to take a picture of the "flying saucer," but since it was still far away and indistinct, he waited. The first object, now followed by a second one, moved rapidly toward Mount Ranier, began to sharpen in outline, and both were soon so clearly visible that he was able to snap his unusual picture. The photograph shows two apparently solid, disklike objects, flattened, brilliantly white but dark at the bottom, apparently linked together by white streamers, skimming toward the mountain peak.

Recognizing the close resemblance between the objects in the photograph and those described, Reed made a full analysis of the weather conditions prevailing at the time the picture was taken. From radiosonde data provided by the Seattle-Tacoma Airport, he obtained measurements of the size of the clouds, their height above the mountains, wind directions, and temperature and humidity at mountain height and cloud height. Obviously the pattern of weather conditions that prevailed that day was suitable for the formation of saucerlike clouds.

To test the hypothesis that also had seen such clouds, he then obtained records of the weather data for June 24, 1947, to determine whether atmospheric conditions on the two dates were basically similar. To be comparable, neither would have as the biome ing from the north; or northwest in Mr. Arnold's case since the pluers were sighted to the south and southeast of the peak. The air would have to be dry at lower elevations and moisture would have to be spreading in a higher levels. An inspection of the historical maps

1. 1. 1. 1. All these conditions were met" [ 97 ]