There’s a mighty big wind blowing in the upper levels of the earth’s atmosphere these days. In fact, it’s been blowing for centuries, but the lack of frequent and dependable high-altitude weather observations precluded an early detection of its existence. This fast-moving river of air flowing around the earth is of vital concern to weathermen, airmen, and military and naval planners, and whether you like it or not, it affects even you.
If the weather on the surface around your house, your garden, where you play golf, or where you work, is of any concern to you, or if you occasionally travel by air and enjoy efficiency, speed, and comfort, you have an interest in the Jet Stream. And if the success or failure of certain types of military and naval operations and missions are of any concern to you (and they most certainly should be), you very definitely have an interest in the Jet Stream!
This high-speed stream of air particles is relatively flat, averaging only about 3 miles in thickness and close to 100 miles in width. Vertically, it is found between three and ten miles above sea level with its maximum intensity usually between five and eight miles above sea level.
The Jet Stream normally blows from west to east, but under certain conditions a Jet Stream will appear blowing toward the west. With wind velocities sometimes exceeding 300 m.p.h. in the core of this phenomenon, it is most important that its location, intensity and movement be known at all times.
This would be a relatively simple problem if the earth were a smooth sphere. This superwind would then, in all probability, follow the latitude parallels. But since the earth is not a sphere with a smooth surface, the problem becomes quite complex. Instead of roaring on a straight horizontal course completely around the hemisphere, the Jet Stream meanders vertically over several thousand feet of altitude as well as in a north-south direction, is usually broken at various points, and frequently gives birth to “Jetlets.”
Like people in the upper income tax brackets, it migrates north and south with the seasons. In the wintertime over North America, its main axis is normally found between the latitudes of Richmond and Miami. South of latitude 20° North, the big wind appears to break down completely. During the summer months it seeks the provinces of Canada. Its southern hemisphere counterpart has also been detected.
Even at this late stage of the game, not too much is known about this relatively new problem child of the weathermen. The foremost meteorologists of our day are still arguing the questions of “what” and “why.” This is easily understandable for the most handicapped scientist is the meteorologist. His laboratory is the vast atmosphere surrounding the earth, and the technique of conducting controlled laboratory experiments is, for the most part, denied him.
As a rule, the people in the weather business do not begin talking in terms of the Jet Stream until wind speeds exceed 100 m.p.h. Although winds as high as 315 m.p.h. have actually been recorded in the Jet, these extreme velocities are fairly localized and do not extend over great distances. The highest velocities generally occur during the winter season between 20°-35° North.
Not satisfied with a seasonal travel program, this snakelike superwind also moves from day to day at right angles to its own axis with a speed of about 10 to 15 m.p.h. The direction of movement can be either toward the pole or the equator.
This, then, is the latest meteorological gimmick confronting today’s weather experts and experts in numerous other fields. Its precise definition even the theorists cannot agree upon, although most will define a Jet Stream as “a relatively narrow zone of extremely strong winds in the upper troposphere.”
If you enjoy life as a free citizen in the greatest country in the world, don’t sell the Jet Stream short! This high-speed stream of air can provide service as “magic carpet” or “brick wall,” depending on which way it’s blowing; for military as well as commercial aircraft, and for enemy as well as friendly planes, vehicles, and missiles. And the much more sinister purposes to which this whistling wind with the wanderlust could be put we can only guess and shudder about. We can assume that the military planners, airmen, weathermen, and other scientists on the other side of the Iron Curtain are vitally interested in this latest meteorological problem child. They, as well as we, realize the potentialities of effectively utilizing the big wind of the westerlies.
Increasing the radius of action and range of aircraft is only one aspect. This can be accomplished by “hooking a ride” on the Jet Stream. All one has to know is where it is, how strong it is, and precisely where it will be during the entire time of flight. The shortest distance between two points does not go hand in hand with the shortest time to traverse that distance.
On his record-smashing flight across the Atlantic last year, Captain Charles F. Blair, Jr. of Pan American World Airways piloted his single-engined Mustang from New York to London in 7 hours and 50 minutes by availing himself of only a segment of the Jet Stream. Remarkable as that time is, he could have done even better that day.
Captain Blair’s route took him from New York to London via Boston, Yarmouth, Sydney, Gander, Weathership “Charlie,” Weathership “Jig,” and Shannon. Only in the vicinity of Weathership “Charlie” was Blair in the core of the Jet, and at that time a radar plot of his ground speed showed his plane to be streaking along at 600 m.p.h. Had Blair started ouf across the Atlantic from a point about 120 miles south of Gander and taken an east-northeasterly heading from there, he would have been in the core of the Jet Stream a much longer time and, consequently, would have taken even less time to get to London. Upon his arrival at London, Captain Blair noted that he still had enough gas to go on to Moscow and return to Berlin. All this, mind you, was accomplished in a single-engined, propeller-driven aircraft utilizing only a small portion of the Jet Stream. The implications of jet and turbo-prop bombers making a 100% utilization of this superwind suggest over-the-ground speeds up to 1,000 m.p.h.
Quite naturally, this whistling wind with the wanderlust will not always be blowing in precisely the right direction, but that in no way decreases its importance. If it’s bad for you, it might be wonderful for “the other guy.” If it is, you must know just how wonderful, for how long, and where? Then too, if you can avoid a 280 m.p.h. headwind, a veritable “brick wall,” that’s money in the bank.
And perhaps the sinister purposes to which the Jet Stream could be put by military scientists, which you and I can only guess about, outweigh them all.
On numerous occasions during World War II, both over the continent of Europe and in the western Pacific, allied bombers came in contact with this unrecognized and, of course, unforecast, superwind. They were either blown way off course or held almost stationary aloft. Upon their return to base, flight crews insisted that there was a terrific wind blowing upstairs, but the wind speeds they quoted seemed entirely unreasonable and theoretically impossible to the forecasters. These reports, the forecasters usually filed with tongue in cheek and attributed to poor navigation on the part of flight personnel. As a result, a feeling of mutual distrust frequently arose.
It also happened on several occasions that the bombers never did reach their targets because of this tremendous wind. Sometimes, too, the Jet Stream wreaked such havoc with the rendezvousing of bomber and fighter aircraft that the bombers were forced to accomplish their missions without benefit of fighter cover.
The commercial airlines are already giving all due respect to this big wind of the Westerlies, and as time goes on, its importance in flight planning will skyrocket. The jet transport, operating at high altitudes and travelling at high speeds, is no longer something to tell our children that they will live to see. It’s here. At the present time, Canada and Britain are far ahead of the United States in this field.
Right now the British are producing more than 40 jet transports of the Comet I and Comet II types. Jet aircraft passenger service to South Africa and Egypt has already started. Even Queen Mother Elizabeth and Princess Margaret have already experienced the new sensation of jet aircraft travel. As more Comet II types become available, it’s likely that British jet aircraft transport routes will go through India, Singapore, and perhaps even to Australia.
Two of the major advantages advanced for air travel by the airline publicity departments are speed and comfort. These two items are practically guaranteed. Speed is a wonderful thing, but I hate to think back to the numerous occasions on which I arrived in a city to make air connections and was obliged to sit in a dumpy terminal for what seemed like hours because of an unforecast wind. In the case of high-altitude jet transports and the Jet Stream, it might well be hours.
There’s no getting around it; the Jet Stream is being and will continue to be encountered and necessarily coped with and not on an occasional basis, either.
Can you imagine having a midnight snack in New York, an early breakfast in London, an appetizing lunch in Cairo, and afternoon tea and crumpets back in London again? A portion of this schedule has actually been accomplished. A little over a year ago, test flights were made by the British (London to Cairo and back to London) and exactly that type of schedule was met. The people who were on that flight said it was a most wonderful new sensation. They didn’t suffer the usual fatigue that goes with a long trip by air. Fatigue is caused by the continuous vibration. In a jet aircraft, vibration is almost non-existent.
But even more important than the aspect of speed from the standpoint of the commercial airlines is passenger comfort. No comfort—no passengers—no money—no airline; it’s that simple. And this new weather wrinkle termed Jet Stream poses a serious threat to passenger comfort.
If an airline passenger experiences severe bumpiness and gets bounced all over the sky or perhaps ends up with someone else’s tray of food in his lap, it will probably be a long time before he chooses to travel by air again.
It is strongly suspected that severe bumpiness occurs in places along the boundaries of a well-developed Jet Stream. This turbulence has already been encountered by military jet planes. There is also good reason to believe that moderate bumpiness is present in the general area of the super-wind.
The unfortunate thing is that there are no visual indicators, such as a particular cloud form, to show the pilot where the severe bumpiness is present or just how bad it is. It can’t be picked up by radar either. This, in itself, poses quite a problem. One can’t expect airline passengers to have their seat belts fastened all the time, but perhaps that will be the initial solution.
One of the answers, obviously, is to know exactly where this high-speed stream of air is, what its intensity is, and where it is likely to be for the duration of the flight.
Even more important than the aspect of comfort is that of safety. With any type of jet aircraft, be it fighter, bomber, or transport, a most critical item is fuel consumption. These aircraft gobble fuel like a youngster with a dish of ice cream. And when the Jet Stream is blowing in the wrong direction for the flight, the plane will have to detour around the core of these violent winds.
But it is also a new forecasting tool for the weatherman in addition to being a problem child. The Jet Stream has a tendency to meander, and when this meandering becomes excessive, it invariably breaks down. A counter-clockwise circular motion of cold air then develops to the south. These cold vortices at high altitudes are of tremendous importance to the weathermen in predicting the weather at the earth’s surface.
Weather fronts, which are nothing more than narrow zones of transitions between different air-masses, are largely affected by this superwind. When an intense Jet Stream and a couple of other weather phenomena are in phase, a very rapid intensification of a surface low pressure area of bad weather can be expected. There is also strong evidence that the waves which tend to develop along weather fronts are actually “steered” by this violent wind of the upper atmosphere, and that a strengthening of the Jet Stream leads to an intensification of the associated surface weather front.
It wasn’t until late in the 1930’s that weathermen had available to them an instrument called a radiosonde. This balloon- borne device continuously transmits temperature, pressure, and humidity information to ground receivers as it soars to heights exceeding 60,000 feet. And it wasn’t until several years ago that the network of radiosonde stations was sufficiently great to supply the required information concerning the jet stream.
Then shortly after World War II, the radiosonde was supplemented by “rawin,” a specially designed radar reflector borne aloft by a balloon and tracked by land stations and ships at sea to determine wind conditions at high altitudes. Until that time, winds aloft were obtained by visually following a balloon with an instrument called a theodolite. If a cloud got in the way, the observer usually lost the balloon. On rainy days with a low overcast or when there was fog, high- level wind data were completely lacking.
It must be admitted that a lot is yet to be learned about this latest weather phenomenon. In addition to the facts already mentioned however, it is known that wind speeds diminish very rapidly both to the north and to the south of the Jet Stream, the decrease being greater on the north side. It is not at all uncommon for the wind to decrease 120 m.p.h. in a distance of only 100 miles. An even more pronounced change of wind speed is present in going vertically above and below the core of the Jet Stream.
The temperatures around this superwind are not, perhaps, what you would immediately expect. To the north, the air is warmer; and to the south, colder. It is thought that the zone of warm air to the north of the Jet Stream causes a secondary maximum wind to generate in that area.
Credit for the “discovery” of this latest phenomenon of the weather business goes to the Department of Meteorology at the University of Chicago.
Finally, it can be stated that there is a great deal being done to learn more about this latest problem child of the weather wizards. It is being studied from all angles and kept under close surveillance by the U.S. Weather Bureau, several universities, and the weather services of our Armed Forces.