Page:Ruppelt - The Report on Unidentified Flying Objects.djvu/132

 part of the radar wave to travel in a big arc and actually pick up the ground many miles away. Or it can cause the wave to bend down just enough to pick up trucks, cars, houses, or anything that has a surface perpendicular to the ground level.

One would immediately think that since the ground or a house isn’t moving, and a car or truck is moving only 40, 50, or 60 miles an hour, a radar operator should be able to pick these objects out from a fast-moving target. But it isn’t as simple as that. The inversion layer shimmers and moves, and one second the radar may be picking up the ground or a truck in one spot and the next second it may be picking up something in a different spot. This causes a series of returns on the scope and can give the illusion of extremely fast or slow speeds.

These are but a few of the effects of an inversion layer on radar. Some of the effects are well known, but others aren’t. The 3rd Weather Group at Air Defense Command Headquarters in Colorado Springs has done a lot of work on the effects of weather on radar, and they have developed mathematical formulas for telling how favorable weather conditions are for “anomalous propagation,” the two-bit words for false radar targets caused by weather.

The first problem in analyzing reports of UFO’s* being picked up on radar is to determine if the weather conditions are right to give anomalous propagation. This can be determined by putting weather data into a formula. If they are, then it is necessary to determine whether the radar targets were real or caused by the weather. This is the difficult job. In most cases the only answer is the appearance of the target on the radarscope. Many times a weather target will be a fuzzy and indistinct spot on the scope while a real target, an airplane for example, will be bright and sharp. This question of whether a target looked real is the cause of the majority of the arguments about radar-detected UFO’s because it is up to the judgment of the radar operator as to what the target looked like. And whenever human judgment is involved in a decision, there is plenty of room for an argument. All during the early summer of 1951 Lieutenant Cummings “fought the syndicate” trying to make the UFO respectable.

AU the time I was continuing to get my indoctrination. Then one day with the speed of a shotgun wedding, the long-overdue