Why we’re getting more disastrous hurricanes
Once we thought hurricanes belonged to the tropics. But we’ve had ten in three years and weather scientists suspect that’s not all. Here’s a disturbing report on
Until recently Canadians paid little attention when their radios and newspapers reported a new hurricane forming in the West Indies. Hurricanes, they felt, were a tropical menace of no concern to Canada, like sharks and crocodiles. In fact, there's a story about a Nova Scotia man who bought a barometer from a mail-order firm and sent it back in disgust because it arrived predicting “hurricane.” It was a fraud, he said, because hurricanes never reached this country. But the barometer was more accurate than he knew, for it was September 6. 1953. and half a day later a hurricane called Carol ripped through the Maritime provinces, doing tremendous damage.
Today that barometer would be readily believed. and when there is a hurricane report on the radio, Canadians cock an attentive ear, for in the three years since Carol lambasted the Maritimes, eastern «Canada has been lashed by ten lusty hurricanes, including the notorious Hazel which killed more than eighty people around Toronto in October 1954.
Before 1953 about one out of every ten hurricanes born in the West Indies and the Caribbean came as far north as Canada before dying out; but Canadians hardly recognized them as hurricanes because, by the time they hit, most had petered out to stilf gales. Since 1953, however, about one in three hurricanes originating in the south have hit Canada, and some of these have delivered a Sunday punch.
Whether this increase is a passing phenomenon or permanent has still to be determined by scientists. Most weathermen are beginning to suspect that hurricanes, always perverse and unpredictable, are changing their ways, and that Canada and the northern U. S. will continue to sec more of them in future. “U. S. meteorologists are studying this thing more than we are, because they are closer to hurricane sources and more concerned.” says Keith T. McLeod. Department of Transport superintendent of weather services in Toronto. “They are turning up evidence suggesting there is much more than chance or accident involved in recent hurricane developments.” Many meteorologists think that the tendency for recent hurricanes to lunge farther north than formerly is part of a bigger picture in which they see North American weather abandoning some
of its traditional patterns. They say that northern hurricanes, milder winters and moderating climate may all be linked together and stem from the same source—a shifting of the upper altitude's globe-encircling jet stream that is causing more frequent invasions of tropical air into our traditionally Arctic-dominated Temperate Zone weather.
While weathermen ponder the cause, insurance men are ruefully studying the effects. Wind insurance is grouped with fire, water and hail in a single comprehensive type of policy. The cost has been decreasing steadily for years because losses from fire, the main hazard, have been going down. Insurance officials say there arc no detailed breakdowns, but even without these it is obvious that wind losses are rising. An official of the rate-setting Underwriters Adjustment Bureau in Toronto says increasing wind losses may soon offset fire savings and start insurance costs rising again.
Hurricanes occur from June to November, but more than eighty percent of them come during the hurricane season's peak months of August, September and October. Will this year produce a repeat performance of what occurred during the past three? Meteorologists and insurance underwriters are waiting anxiously for the answer.
Hurricanes have taken us somewhat by surprise, and many Canadians are asking: What are they?
In many parts of the tropics, air masses that lie motionless for long periods over warm seas sometimes develop spontaneously into extremely severe and compact storms notorious for violent winds and rain. They must have tropical seas for their birth and meteorologists call them “tropical cyclones.” But throughout the world they are known by a variety of names. In the Pacific Ocean they are called typhoons, in the Indian Ocean they're known as cyclones. Australians call them willy-willies, and the West Indies calls them hurricanes.
Hurricanes have the same general anatomy as any storm—a central zone of low air pressure with a large doughnut-like ring of wind revolving around it. The wind is simply air being sucked into the central “low.” but the earth's rotation deflects it into a spin and it winds up spiraling around and around, the continued on page 51
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Why we're getting more disastrous hurricanes continued from page 22
Over a still tropical sea a vicious circle is set in motion—and another hurricane is born
way water spirals as it drains from a wash bowl.
Low-pressure zones are produced by disturbances along fronts where coldand warm-air masses are colliding, or by uneven distribution of the sun’s heat which has created a pocket of warm rising air. This structure, consisting of a central low with its doughnut of wind spiraling around, may be anywhere from a thousand miles or more across to as little as fifty yards. The big ones are our normal storms which march in a steady procession from west to east around the northern hemisphere, bringing our dayto-day changes in weather. As a rule, the smaller and more compressed they are, the more violent is the wind.
Among normal storms, it is a severe one that can produce a wind of fifty miles an hour. But when the whole structure is compressed so that its diameter is a quarter of a mile or less, as sometimes happens, winds may hit three hundred miles an hour, and the result is a tornado that levels everything in its path. Hurricanes fit between these two extremes. (The term "cyclone," often used erroneously for a severe windstorm, is a general family name for all revolving storms that have low pressures at their centres.)
Violence in a vacuum
Hurricanes, although their winds are not of tornado violence, are the most destructive storms. This is because tornadoes live only an hour or so and cover a very narrow path, whereas hurricanes live for a week or two and cut a swath of destruction one to five hundred miles wide, often spawning a rash of tornadoes along their fringes. Hurricane winds commonly reach one hundred and twenty-five miles an hour, though they are usually reduced to from seventy to ninety miles an hour before they reach Canada. They are further characterized by extreme humidity and torrential rains because of the water vapor sucked up while passing over tropical seas.
As for what causes hurricanes, the weather scientists are not too sure, because the big storms are always born at sea where there are no meteorologists or instruments to observe and record the details. But this is apparently what happens:
In a narrow belt near the equator, air lying on the sea is often heated unevenly by the sun and, wherever a small patch of it becomes slightly warmer than the surrounding air, it begins to rise. In rising it rotates like the little whirlwinds or "dust devils” frequently seen spinning down country roads on hot summer afternoons, sucking up dust and debris as they go. The rising air has actually created a small column of low pressure, and the air spinning around it is moving in to "fill up" this miniature low. When conditions are right, thousands of these vortexes are being produced over hot tropical seas. Most live for only a few seconds or minutes before the pressure is equalized and the low disappears.
But apparently at extremely rare intervals one of these trivial vortexes becomes self-perpetuating. Meteorologists believe this happens when it moves into an area where water and air are very still and the air close to the sea has become saturated with evaporated moisture. When this vapor-laden air is sucked upward, it acts like a fuel, for as it condenses it gives up
heat. This released heat makes the air column rise and condense all the faster; and the faster it rises, the faster it sucks in more vapor fuel from the sea’s surface * below. Once this vicious circle of circumstances is set in motion and a supply
of fuel remains available, the vortex of rising spinning air can do only one thing —keep growing in size and violence.
Many hurricanes-to-be are probably strangled at birth when they move over a cooler area of sea where the air’s
vapor content is low. for at the outset the brewing storm needs constant "refueling." But once the vortex—perhaps only a foot or two across at its beginning— grows into a mature hurricane a hundred miles or so in diameter, its own momen-
tum is then so tremendous that it must move over land or over the cold North Atlantic, permanently cutting off its source of vapor fuel, before it will finally die. But even over land severe hurricanes sometimes rage for a few days before their momentum is spent.
The "low" at a hurricane's heart is known as the "eye." a deceptively clear and quiet zone ten to twenty miles across where there is no wind because here the wind has reached its goal and is being sucked violently upward. While air spirals around the eye to produce the hurricane
wind, the entire hurricane structure is also moving en masse, the way a spinning top moves around the Hoor while continuing to spin. It drifts about slowly at ten to twenty miles an hour, but gradually speeds up to as high as fifty miles an hour.
Hurricanes that reach Canada are born near the equator, in a narrow belt stretching from the Caribbean east across the Atlantic to the vicinity of Cape Verde Islands, off Africa. From their birthplace out at sea most hurricanes follow a curving course, first west toward Florida and
the Carolinas, then finally northeast back out over the Atlantic to blow themselves out at sea. f his was the traditional hurricane path, but recently more and more of them, instead of turning harmlessly to the northeast out to sea. have been following a more northerly path which has carried their devastating punch into northern U. S. and Canada.
The increase apparently began with the great New England hurricane of September 1938, which killed six hundred people and destroyed three hundred million dollars worth of property. At that time Dr.
C. F. Brooks, of Harvard University, and other meteorologists studied the average frequency of New England hurricanes prior to 1938 and worked out the odds against future repetitions. Their findings, which apply roughly to the Canadian Maritimes as well, w'ere that from past experience New England could expect an extremely severe hurricane like the 1938 storm every one hundred and fifty years, and a hurricane of some sort every ten years.
But how have these odds held? The next severe New' England hurricane came, not one hundred and fifty years later, but only six years later, in 1944. Then another. equally severe, hit New England in 1954. Lesser hurricanes, instead of reaching New England every ten years, have been coming since 1938 at the rate of about one every three years.
Statistics for Ontario suggest a similar hurricane increase. According to a recent study by A. H. Mason, of the Canadian Meteorological Service in Toronto, moderate to severe hurricanes entered Ontario at the rate of one every six or seven years during the fifty-year period 1900-1949. In the six hurricane seasons since 1949. however. Ontario has been hit by two (and a third one was a near miss), to produce an average hurricane rate of one every three years.
Eastern Canada as a whole (Ontario to Newfoundland) has been hit during the last three years by ten hurricanes, making it by far the most severe three-year period on record. They began with Hurricane Barbara in August 1953. (Meteorologists, for identification purposes, give girls' names to hurricanes, and the first letter of each name denotes the order in which the hurricane occurred that season. Barbara was 1953‘s second hurricane. Alice, the first one. was a weak sister that didn't get out of the Caribbean.)
Barbara romped up the Atlantic, turned west and did much damage in Cape Breton and Newfoundland. Two weeks later. Carol, a much heftier hurricane, plunged up the Bay of Fundy with eightymile-an-hour winds and did a million dollars damage in the Maritimes in a few hours.
Next year. 1954, three moderate hurricanes came north in quick succession, striking Quebec. Newfoundland and New Brunswick, in that order. And then came Hazel, to parlay a vicious series of tragic coincidences into the most destructive hurricane ever to hit Canada.
Hazel had a charmed life. It was born off the northern coast of South America on October 5, 1954. and zig-zagged erratically around the Caribbean for five days, displaying all the signs of a weakling that would probably die before it got far from home. On October 10 it suddenly sprinted off on a beeline north, heading directly at mountainous Haiti, where weathermen expected it to beat itself to death (mountains usually disperse and kill hurricanes). But Hazel veered, skirted Haiti, picked up new strength and dashed north toward the Carolinas.
According to the traditional rules of hurricane behavior. Hazel should have turned east and blown itself out at sea: failing this, it should have died before
traveling fai overland; or it should have been blocked by the Allegheny Mountains and, if not killed, at least flung out into the Atlantic again. But Hazel survived all the hazards in its path and raced on across Pennsylvania. New York State and into southern Ontario.
Here came the most sinister coincidence of all. While Hazel, a vicious spawn of the tropics, plunged north, a vast mass of cold arctic air was pushing southeast across Ontario toward it. Hazel by now was a circular storm wide enough to reach from Kingston to Windsor. It raced across Lake Ontario at fifty miles an hour, its towering clouds still saturated with water it had picked up from the steaming Caribbean. On the afternoon of October 15 Hazel’s most vicious centre collided with the line of cold arctic air directly over Toronto, Ontario’s most densely populated region. The sudden cooling condensed Hazel's tremendous load of water vapor and Toronto was drenched in the heaviest twelve-hour rainfall in its history.
That night the floods that plunged down the Humber, Credit and Etobicoke Rivers of Toronto's suburbs swept away one hundred million dollars worth ol homes anJ drowned eighty persons. Next day Hazel died, hidden and unobserved, somewhere in the Quebec wilderness east of Hudson Bay.
Four more hurricanes reached C añada in 055. The last one, lone, swept St. John's with ninety-mile-an-hour winds and caused three million dollars damage in Newfoundland.
Blow the man down
Canadians have good reason to be concerned over whether more of the meteorological monsters will continue reaching Canada, for hurricanes strike with a triple punch of waves, wind and rain.
When moving across the sea a hurricane literally pushes the water ahead of it. and storm tides may rise ten to fifteen feet above normal. Coastal areas are flooded and waves pound far inland. In 1737 on the Bay of Bengal, hurricane waves flooded vast coastal areas and are said to have drowned three hundred thousand people. Similar hurricane flooding at Galveston, Texas, in 1900 drowned six thousand.
Maximum hurricane winds are not known because invariably the wind-measuring instruments are blown away just when things begin to get most interesting. Wind velocity reports usually terminate abruptly like this one from a Florida weather station in 1948: “3.40 p.m. Wind one hundred and twenty-four miles per hour, anemometer swept away." Anemometers sensitive enough to measure light day-to-day breezes are no match for a full-fledged hurricane. The highest official recorded hurricane wind was an average of one hundred and eighty-seven miles an hour for a five-minute period during the New England hurricane of 1938. Meteorologists said that to produce this average there would have to be gusts of two hundred and fifty miles per hour or more.
Somet-mes hurricanes not only blow away the instruments but the men watching them too. A log kept at a weather station in the Florida Keys during a 1935 hurricane reads like this: “10.15 p.m. Wind seems stronger, barometer 26.98 inches. The house is now breaking up . . .” Then there is a four-hour gap, and the log resumes: “2.25 a.m. I became conscious in a tree, lodged about twenty feet above ground."
Hurricane rains often cause more deaths than the wind, because of flash floods they produce in rivers. One inch of
rain in twenty-four hours is a heavy rainfall for Canada, yet Hazel dumped seven inches on the vicinity of Toronto. Even this is a trickle to what hurricanes sometimes do. The record was in 1911 in the Philippines—forty-six inches in twentyfour hours.
Hurricanes are always producing surprises. and one of the strangest occurred last year. Meteorologists have always insisted that conditions suitable for the development of hurricanes in the Caribbean and Atlantic are never present earlier than May. A January hurricane
reported by Columbus in the West Indies four hundred and fifty years ago was regarded as an imaginary one that Columbus fictionized in his ship's log to explain damage to his ship caused by a mutinous crew. But now Columbus can rest easier in his grave. There was a January hurricane in the West Indies in 1955, and meteorologists are now forced to admit that the long-derided Columbus hurricane might really have occurred.
Meteorologists are working desperately to determine what steers hurricanes, so that hurricane movements can be fore-
casted earlier and more accurately. Why do some of the big storms spin wildly out of the tropics and lunge into Canada? The weather experts think they have the answer.
It used to be thought that the prevailing westerly winds caught the hurricanes off the Carolinas and were responsible for turning them northeast into the Atlantic. Now meteorologists suspect that the westerlies form only a small part of the steering mechanism.
According to latest theories, there may be two other factors that have played
bigger roles in shaping this typical curving hurricane path. One of them is the jet stream, that recently discovered river of fast-moving air that circles the globe five to eight miles up; and the other is what meteorologists call the “Bermuda high.”
The Bermuda high is a vast oval-shaped, semi-permanent mound of highpressure or "hard” air which sits for long periods over the Atlantic. Its size varies but usually it extends from the latitude of Florida north to around the latitude of Newfoundland, and east and west for most of the width of the Atlantic. The jet stream, which has only begun to be understood with the recent increase in highaltitude flying, is a narrow ribbon of wind high above the earth, twenty miles or so in width, in which air is often moving at three hundred miles an hour. The jet stream passes over the United States from west to east and continues out over the Atlantic until it collides with the western rim of the Bermuda high. This high deflects the jet stream northeast and it makes a big detouring circle, turning back on its eastward path again when it gets north of the Bermuda high somewhere in the North Atlantic.
The jet that tows hurricanes
Hurricanes also are deflected by the Bermuda high, and the curving path they generally follow is determined by the location of the edges of the high. When a hurricane has curved north around the high and arrives off or over the Carolinas, it is believed that the hurricane’s top story is grabbed by the jet stream’s threehundred-mile-an-hour winds, and the storm is literally dragged along by the scruff of its neck.
In the old days the point where the jet stream met the Bermuda high was usually well offshore, so that most hurricanes were dragged northeast before they reached land. Now the Bermuda high seems to be spending much more of its time sitting with its western edge close to or directly on the U. S. Atlantic coast. This means that hurricanes drift farther west before they are turned north, and this western drift is bringing more of the big tropical storms ashore. So now, when the jet stream grabs the top of a hurricane, this is much more likely to occur over the southern U. S. mainland, and then the northeast drag, instead of carrying it to sea, carries it straight up the coast through New York State. New England and into eastern Canada.
The man who has done most of the work investigating the jet stream’s apparent effect on hurricane paths is Jerome Namias, the U. S. Weather Bureau’s chief of long-range forecasting. Namias, in his recent thirty-day forecasts, has stuck his neck out much farther than most weathermen are willing to do, but he refuses to make any forecasts about possible future behavior of the Bermuda high, the jet stream and the hurricanes they are believed to steer.
He says merely that the edge of the high and the jet stream form an atmospheric funnel, drawing tropical air north, that the funnel’s average position has shifted landward since the late 1930s and that it is probably responsible for the Atlantic coast's milder winters in recent years as well as for its increase in hurricanes. But the reason for the funnel's shift and whether it has permanently shifted are questions that have Namias and his colleagues still wondering.
Canadian weathermen are wondering too, but not with much optimism. For meanwhile they are warning eastern Canadians that there are probably more Carols and Hazels on the way.