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June 2, 2006

Strange But True!

Q. Discovered by airmen during World War II, these move at up to 370 kilometers per hour (230 mph) at heights from 10-15 kilometers (6-9 miles), in narrow bands where the troposphere meets the stratosphere. Their energy comes from the heat differential from equator to poles, bestowing this planetary “free ride in the sky,” averaging 100 mph in winter, 50 in summer. What are they, and what was their role in the War?

A. They're the “jet streams,” generally blowing out of the west, often thousands of kilometers long, hundreds wide. Pilots know them as a potential helpful tailwind, the prime reason it usually takes about an hour longer to fly from New York to Los Angeles than from Los Angeles to New York.


 
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