No CrossRef data available.
Published online by Cambridge University Press: 18 January 2010
The main meteorological features of the atmosphere from 50,000 to 70,000 ft. which are likely to be of importance to supersonic aircraft, are the ‘polar-night westerlies’ and the abrupt rises in temperature which take place in late winter in latitudes polewards of 50° or 60°.
The polar-night westerlies blow between 50° and 70° latitude and reach high velocities, increasing with height, from 60,000 ft. during the winter months; towards.the end of the polar night there is often a sudden rise (perhaps as much as 40° C.) at about 85,000 ft., which spreads downwards and is eventually associated with the termination of the polar-night westerlies.
The increase of speed of supersonic aircraft, as well as the decrease of variability of the wind with time at heights above 50,000 ft., have remarkable effects on the punctuality of arrival of aircraft. For instance, on the route from London to New York, the probable error due to wind in arrival time of a 1500-kt. aircraft at 50,000 or 60,000 ft. is about half a minute. This is in contrast with a probable error of ten to fifteen minutes for a 400-kt. aircraft flying at 30,000 ft.