The Air Force has a different problem. Like the Navy, they are dedicated to the task of getting vital weather data for the forecasters, but their own problem is to evacuate military aircraft from threatened bases and get information needed for aeronautics. Also, they have the responsibility of giving weather forecasts and warnings to the Army. Until a few years after World War II, the Air Corps was a part of the Army, and when all three services were joined in the Department of Defense, the Air Force kept the weather job for both departments as a matter of economy and efficiency. Therefore, for this and other reasons, the Air Force follows a hurricane-probing plan which differs from the Navy’s.
Flying generally at higher levels in tropical storms, the Air Force, as much as the Navy, puts a great deal of reliance on radar, which has become a marvelous aid in watching the weather. In the beginning—years ago—radar was not designed for weather purposes, however. During World War II, radar was used to spy on enemy ships and aircraft in fog or in darkness, to distances of 150 miles or more. The high-frequency rays sent out by the radar strike the object and are reflected back to the transmitter, where a sort of a silhouette appears on a scope. It may be black with white areas showing images of solid objects, such as planes and ships. In those days early in World War II, the weather was a nuisance to the radar people. It often seemed to interfere with the use of radar for military purposes, but the operators soon learned that the interference came from rain drops in local or general storms and that the rainy areas could be located and followed on the scope and, with the proper design, the apparatus could be used as a weather radar.
The first experiments with radar carried on board aircraft in organized tropical storm reconnaissance were made in 1945. Within three years, all the planes were carrying radar sets and had crew members whose sole business it was to watch the radar scope and tell the pilots and weather officers what kind of weather lay ahead.
Scarcely had these observations begun when the radar weather men discovered an amazing fact. On the radar, a tropical storm looks like an octopus with a doughnut for a body and arms that spiral around the body as if the creature had been caught in a whirlpool. These arms are bands of squally weather, oftentimes violent turmoil. Between the bands (or octopus arms) the wind is furious, of course, but there is less turbulence and cloudiness, and here the aircraft is in much less trouble than in the squall bands. The cause of these violent bands spiraling around the center has not been figured out yet for sure, but all tropical storms have them, and the hunters are beginning to understand them better.