Science: Peculiar Weather

Britain was emerging last week—it hoped—from the worst, triple-threat winter its weathermen could remember. The heaviest snowfalls since 1880-81 had blocked the railroads, cut the highways, slowed the whole nation's life (TIME, Feb. 10). It was the coldest winter since 1870. In March a howling, 73½ m.p.h. wind set a 35-year record at London.

The worst was probably over, though Britain was half-afloat with record-high spring freshets. But all winter Britons had huddled around their feeble fires and cursed the un-British weather for turning their wet green island into an offshore Siberia. The complaint was no exaggeration. Britain was actually getting Siberian weather. Across the Atlantic, eastern Canada got tastes of the warm, sloppy winter which Britain normally enjoys. Why the switch in weathers?

Normally, the wind blows over the North Atlantic from west to east, crossing the warm Gulf Stream and giving Britain its mild "oceanic" winter. This .year, according to the U.S. Weather Bureau's Jerome Namias, the "prevailing westerlies" failed; cold east winds from Russia invaded western Europe. They crossed the narrow North Sea (which did not warm them much), left Britain frozen and snowbound, continued on across the ocean. By the time they reached eastern Canada, they had picked up the Gulf Stream's warmth.'

Britain was the worst but not the only sufferer. Much of northern Europe has been extra cold this year. Meteorologist Namias explains it as "a hemisphere-wide aberration of circulation which is producing peculiar weather. . . ."

Cold Cap. The polar region is covered in winter with a cap of cold air which usually reaches down to north latitude 60° (southern Norway and Leningrad). North of this boundary, the wind blows most often from east to west. South of the boundary, the "prevailing westerlies" blow.

This winter, the polar air mass was much bigger than usual, bringing the polar east winds down to latitude 45°. well south of Britain. Along with the cold came a belt of storms, where the east & west winds meet. Winter storms which normally plague Iceland were felt as far south as Bermuda. Britain's record storm was one of these. In a normal winter it would have passed far to the north.

On the other side of the pole, the polar air mass bulged into Alaska, bringing record cold of -83°. In February it swept through inland Canada, through the central U.S. as far south as Florida and Texas. Except for New England, which shared eastern Canada's warm east winds, the eastern U.S. was colder than usual.

Polar Watchtowers. Meteorologist Namias does not know what made the polar air mass grow so big this winter. For months, plotting variations from normal pressure all over the northern hemisphere, he watched it grow, noting "an excess of air mass" moving northward.

In a year or so, meteorologists may know more about the globe's closely interrelated weather. Recently, Canada and the U.S. announced that they would cooperate in maintaining weather stations near the pole itself (TIME, March 17). From these will come inside information on bulging polar air masses.