High Winds

Scientists have long thought that the outer edge of the atmosphere was a quiet place. Little wind, they thought, ever blew there. They knew that at 100,000 ft. the temperature hovered at -- 40DEGF rose to zero at 120,000 ft.; that air density there was only 1/180 of what it is at sea level.

But last week, University of Chicago Meteorologist Herbert Riehl, 44, reported that the high, thin air above 100,000 ft.

is swept by raging, 130-m.p.h. winds that blow fiercely for a day or a week, then subside inexplicably into dead calm--then reverse themselves and blow in the opposite direction.

Violent Changes. Like so many things in the age of space, Riehl's discovery came in the course of a project designed to study something else. The Office of Naval Research, the National Science Foundation and the University of Chicago organized Operation Skyhook 60, which envisioned sending two huge balloons, each more than 400 ft. high, from an aircraft carrier to a height of 120,000 ft. for the purpose of studying cosmic rays. It was essential to know what weather conditions were at that dizzy height so that destroyers and search planes could be deployed to rescue the gondola when it was cut loose. Named chief meteorologist for Skyhook, Riehl set up his headquarters in Puerto Rico, and established contact with ten other weather stations ringing the Caribbean. These stations were furnished with special, high-altitude sounding balloons. At an agreed hour every day, the balloons were released from all eleven stations and tracked by radio. The data were passed on to Riehl, and plotted on an overall map. "We were totally unprepared for what we discovered," admits Riehl. "It was amazing."

Fifteen years ago, Riehl was a member of the team headed by the late Carl-Gustaf Rossby that studied and plotted the jet stream circling the Northern Hemisphere at an altitude of 30,000-40,000 ft. and at velocities of more than 400 m.p.h. But these new winds were far more erratic, though not so violent. For the first ten days, an erratic rush of air flowed west over the Caribbean to the Pacific, at velocities ranging from 30 to 130 m.p.h. On the eleventh day, the southern stations reported that the air above them had abruptly reversed direction, was now flowing eastward. Soon a shear line (the demarcation line between two opposite-flowing air currents) worked its way northward through the stream until the entire stream was blowing from west to east. Next day the stream again reversed itself, blew once more out of the east.

Higher & Faster. Dr. Riehl's new knowledge served Operation Skyhook 60 well. From his San Juan headquarters Riehl radioed to the task force the positions to take for the launchings.

Like the lower-altitude jet stream, Riehl's new wind currents are estimated to be about 300 miles wide, and seem to blow in layers, with the fastest-moving air sandwiched between two slower-moving bands. While the jet stream blows primarily from west to east, the high winds usually blow in the opposite direction. But Riehl admits that he has made only a beginning. The balloons reached only 120,000 ft., and Riehl thinks that wind velocities may be still higher beyond that altitude. "Actually," he says, "we probably were mapping only the lower part of the band."

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