(4 of 9)
M.I.T.'s meteorology department, now a large and flourishing academic province, then had a faculty of two: Rossby and Kurd Willett. They roomed together in a Boston apartment, worked and played together. Soon Rossby began seriously dating Harriet Marshall Alexander, the pretty daughter of a Boston physician, who attracted him initially by her ability to identify from their songs 40 different kinds of birds. Roommate Willett dated Harriet once. When he returned late that night, Rossby was waiting up for him. "I shall kill you!" cried the passionate Swede. Willett withdrew, and Rossby married the girl. (They have three children: Stig Arvid, 25, a physics student at Illinois Institute of Technology; Hans Thomas, 19, a science student in a school near Stockholm; and Carin, 16, a student at the University of Chicago Laboratory School.)
After the romance was settled, Rossby and Willett remained friends and began plotting a major attack on the atmosphere. The Bjerknes theory was based almost entirely on ground observations, but the great air masses that it deals with go practically to the top of the atmosphere. Rossby reasoned that study of wind pressure, temperature, etc., at high altitude should show new facts about the atmosphere's large-scale circulation. This was the time of the great Dust Bowl drought of the '30s, and Rossby's project got support from the Department of Agriculture, which hoped to forecast droughts and other weather disasters.
Facts from aloft proved hard to get. So M.I.T. hired a Cessna. With Willett as pilot, he and Rossby made weather-observation flights every morning from East Boston Airport. The Government soon took over and expanded this work, but the real solution of the problem was the radiosonde. Developed in the '30s, these light, expendable radio transmitters were carried to great heights by small balloons. All the way up they reported pressure, temperature and humidity by radio, and their drift measured the winds aloft.
Grand Pattern. At first the upper-air weather looked as confused and chaotic as weather on the ground. Then a grand pattern began to appear of gigantic horizontal waves in the eastward drift of air that circles around the earth in north temperate latitudes. These are the Rossby waves, also called "long waves." There are generally four or five of them festooned around the polar region. As they shift their positions, they steer the movements of cold and warm air masses that control the weather in the North Temperate Zone.* If the tip of a wave reaches too far south, a great mass of polar air is apt to get broken off. Revolving counterclockwise, it drifts far into the tropics.
By means of elaborate mathematical reasoning. Rossby evolved an equation that could be used to predict the shifting of the waves (see box). Since large-scale weather phenomena depend on this shifting, Rossby's equation made it possible, at least theoretically, to forecast well in advance most of the world's weather patterns. His first paper on the subject, published in 1939, is looked on by meteorologists as a major breakthrough.