Waves on the Job

After basking during late December in springlike warmth, with lawns still green and rosebushes foolishly budding, the Mississippi Valley and the U.S. East Coast last week got gales and snow and cold waves, and the spell of bad weather swept east as far as Russia. The reason for the turnaround, according to Meteorologist Jerome Namias of the U.S. Weather Bureau: the planetary wind was on holiday during the holidays. Now it is back on its job and trying to make amends.

The planetary wind is the broad river of air that circles around the earth at high altitude in the North Temperate Zone. Its general direction is from west to east, but its flow is usually distorted into great horizontal waves 4,000 miles from side to side. The waves have the important function of mixing cold Arctic air with warm air from near the tropics. If the mixture did not exist, Canada would be much colder than it is and Cuba would be hotter.

Fast Jet. In late December, says Namias, the waves in the planetary wind were feeble and lethargic. The wind blew almost due east across the U.S., and since its energy was not dissipated in zigzag waves, it blew unusually fast; the jet stream, its fast-moving core, was clocked at 170 m.p.h. But the mixing effect of the wind was almost nil. The Arctic kept its cold air and grew colder and colder as its heat radiated into space, while the U.S. stayed warm. The port of Green Bay, Wis. was open for navigation on Dec. 29, the first time since 1877. New England had weather 15DEG to 18DEG above normal, and such notorious cold spots as Montana were mild.

This was too good to last, Namias knew. He kept his eyes on the Pacific, and about the end of December he saw what he was looking for: a great wave in the planetary wind. It was moving toward the U.S., and when it arrived it would surely drag down from the north a vast amount of the bitter cold that had been accumulating there. So on Dec. 30 Namias predicted that during January the U.S. east of the Rockies would get extra-cold weather.

Two days later the wave was over the U.S. Cold air from Alaska swept to the Gulf of Mexico and mixed with warm, moist air there. Such mixing always causes meteorological fireworks. During Jan. 2-3, Florida and Cuba had one of the worst winter storms on record, with 70-mile gusts uprooting palm trees and drenching Havana hotels with salt spray. No sooner had the storm got out of the way than another formed over Texas and moved east. Snow fell in Fort Myers, southern Florida for the first time on record. Florida children were released from school to enjoy the unusual sight. Tourists in Miami shivered in expensive, unheated motels and wished they had stayed home.

Extra Push. When the ill winds moved over the Atlantic, they blew a little good. The jet stream high overhead was still moving unusually fast, and it got an extra push from the two near-hurricanes that had formed when cold air from the north mixed with tropical air. A British weather ship stationed 600 miles west of Ireland reported a 230-mile wind blowing eastward at 34,000 ft. Transatlantic airliners, hooking rides on it, broke record after record. A turboprop Britannia of British Overseas Airways made the first commercial New York-London flight in under eight hours. A few days later an El Al Israel Airlines Britannia rode the jet wind from New York to London in 7 hr. 44 min.

In an I-told-you-so mood, Namias predicts that the rest of January will be on the violent side. There is still a lot of the cold air in the Arctic that needs to be mixed with southerly warm air, and the planetary wind is flowing in waves that can do the job.

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