HURRICANES are now in season

New Zealand Listener, Volume 37, Issue 937, 26 July 1957, Page 6

HURRICANES are now in season

HIS is the text of a talk broadcast from the Main National Stations of the NZBS by R. G. LISTER (right) as background to reports of the destruction caused in southern Louisiana by the first hurricane of the 1957 season

Y #StERDAY morning prought news of the death and destruction left by the first hurricane of the season in the Gulf of Mexico, and gave us a grim reminder of the fact that, with all our modern equipment and our scientific method, we have a long way to go before we can control Nature in its wildest moods. Because they are capricious and unreliable, they are given girl names, and the recent one is named Audrey, the capital letter A denoting that it’s the first of the season-the next will be a B, and so on. The forces generated vastly exceed the energy released by any atomic explosion. Of course, hurricanes begin in a small way, and build up energy as they develop and move away ‘from their source Tegions, in the humid tropical seas, and they eventually decrease in violence as they reach cooler latitudes, having left behind them a terrific trail of destruction if their course happens to take them on shore. As a matter of fact, we seem to be in the throes of a particularly bad spell of hurricame violence in recent years. Fortunately for us, New Zealand is on the outer edge of the region likely to be crossed by them south of the Equator, but the last year or two in the Western Pacific and the Western Atlantic have been among the worst hurricane years on record.'In Eastern

Asia they are known as typhoons and tremendous damage is done on the China coast and across Japan every year as they pass northward in a curved trail essentially similar to the tracks across’ the West Indian waters to the Eastern States. Just why the last few years should have seen more violent and destructive hurricanes than before is not at all clearly understood, but it has been suggested that there is a connection with sunspot activity (not with atomic bombs) and that 1957 is the year of peak sunspot intensity after 40 years of increasing incidence-after which a decline is expected for the next few decades. It has been claimed that the strong and regular westerly winds moving across northern latitudes are affected by the sunspots, to the extent of causing a more northerly. swing across the continental areas, so opening up a more northerly path for hurricanes to follow from the south. This is no more than intelligent guesswork at present. However, the alarming damage and destruction in the United States and in Japan has drawn public attention to the need for action over the whole matter.

The first international conference on typhoons has been held in Tokyo, and Programmes have been launched in both countries to improve methods of detection and forecasting. It is hopéd eventually to reach a deeper understanding of the nature of hurricanes, their origin and movement, and this in turn may even indicate ways and means of modifying their development and direction. Mastery of the menace of hurricanes is an inspiring goal. In the United States, the immediate cause of official action was the loss of life and property in the populous and most fully built-up industrial areas of New England, damaged in 1955 and again in 1956-regions further north than those anticipating occasional hurricane devastation. This provided the impetus to establish the National Hurricane Research Project-a joint effort by the Weather Bureau and the Defence Department, financed by a sum of half a million dollars. to be spent on research and investigation, including setting up a chain of special radar stations and new weather stations around the Caribbean and in the southern States. Their observations on the. ground will

be supplemented by the findings of three specially equipped research aircraft, which will make two or three flights weekly across the Gulf and Caribbean areas where the hurricanes are born. Already, ever since the war, the Air Force has run routine hurricane reconnaissance flights from Florida and San Juan, and the Navy flies its own aircraft, too. Once an incipient hurricane has been located all three special research aircraft’ will have the hazardous task of flying in daily to obtain data at various’ levels up as far as 45,000 feet. These aircraft have precision navigation aids for accurate locating; they

will have equipment to take ocean temperatures even from 2000 feet up-be-cause it is believed that appropriate surface conditions have much to do with the initial development of a hurricane and at present it appears that locally an ocean temperature of at least 80 degrees must be recorded; new devices to record vertical windspeeds within the hurricane have been installed, and each plane contains the necessary computing machines to facilitate the preparation of the data in suitable form for the forecaster by the time it returns to base. At the base, in a renovated Casino building at West Palm Beach, Florida, there is a special staff of some 30 meteorologists working on the project, and they have the co-operation of teams of experts at five universities who act in a consulting capacity. It is expected that the first three years will be spent collecting all possible data; then a couple of years working on the amended material, testing theories, and analysing results. At present it is known that hurricanes and typhoons originate about 50 degrees north and south of the Equator, except in the South Atlantic, where conditions for some feason as yet not understood, do not give rise to them. They form over a warmed ocean surface, where the air has become saturated with moisture, and any local rising warm air produces condensation and rainstorms. Many bodies of such rising air cause squally conditions, and nothing more comes of them while others seem to set up a chain of events that lead on to further falling pressures, and an anti-clockwise circulation is set up. The condensation as the air rises releases heat, and supplies the energy for the incipient hurricane. Why this should occur in some places and on some occa~sions and not in others remains a mystery. Conditions in the upper layers of

the atmosphere must somehow be also just right, in order to supply the necessary impetus, Even so, there may be 10 days of stormy weather before the hurricane has really got organised and is under way. Data on this early period is vital, and so far quite inadequately collected. In 1937 Coast Guard cutters were actually sent out in an attempt to get such data-but the attempt was soon abandoned. During the war‘in both Pacific and Atlantic theatres, regular reconnaissance flights were made, and some amazingly good radar photographs looking vertically down on to incipient hurricanes were obtained) but these did little more than introduce scientists to the problems ahead. Once the hurricanes are under way, the forces generated become staggering. Rising air in the central area may carry up moisture at the rate of a million tons per second, and the peak fury of the destructive winds at ground level is felt at up to 10-15 miles out from the centre or "eye" of the hurricane, with winds’ of 125 m.p.h., and local gusts that reach over 200 m.p.h. As far out as 75 miles from the centre, gale force winds are experienced. The whole circulating system may travel across the ocean at 20-25 m.p.h. with the heaviest downpours occurring as a "rain-shield" just ahead of the "eye," bringing as much as 2 inches of rain per hour. Within the "eye" at the centre, there is usually an area about 20-30 miles across of comparatively calm air, and clear skies, all around which dense clouds are seen towering up to 30,000 feet. It is planned to drop special balloons, with radio transmitters into the "eye" of hurricanes, where they may be trapped, and can be used to send out continuous weather reports. Rockets are being used to’ go up to 70 and 100 miles above the hurricanes, equipped to take motion pictures as they go, in

a nose cone that can be later located and recovered by the Navy as it floats in the sea, sencing out messages from its own small radio transmitter. By these means it is hoped to reconstruct a continuous three-dimensional picture of the progress of hurricanes. The violent circulating winds whip up the surface of the sea particularly to the right of the path of the northern hemisphere hurricanes, and a storm surge is normally piled up, which may reach 10 or 15 feet, above the expected tide levels along the coasts and is often the most destructive part of the storm. Not until 1954 was any organised attempt made to chart these storm surges as they passed up the coasts. Obviously, forecasting the direction of movement of a whole hurricane system is the critical task of the weather men, and much criticism has been levelled at the forecasters for lack of accuracy. No firm principles can so far be used, however, and in any case, adequate reports have often been lacking, particularly when a hurricane is moving well off-shore. The course of such a storm, too, is often highly erratic; last year the hurricane "Carol" was "dawdling" for four or five days off South Carolina when it quite suddenly made an overnight dash of 500 miles northwatd to New England, sweeping up the coast, bringing floods as well as violent winds. It was 2.0 am. when the Weather Bureau realised it was suddenly moving, and it was impossible to warn people then. Damage and loss of life resulted on a terrible scale. Radar echoes from rain-drops, and on a radar-screen may be seen the pattern of the rain distribution around the storm centre. A series of radar stations is to be set up. Some large industrial concerns have installed their own radar detection

equipment in the coastal regions, as it pays them to know just when to expect to close down their plant, and do it in an orderly fashion; or, in view of a general warning in the region, to watch for themselves the course of a hurricane and decide not to close down if it passes possibly 100 miles away-in such an event, saving enormous sums ef money by carrying on. The most promising lines of research on forecasting hurricane movements lie in the field of an elaborate assessment of the entire forces in the atmosphere surrounding the hurricane, and a prediction of tendencies in pressure changes ahead of it, for it seems that movement is strongly influenced by conditions all around. With adequate data, it seems quite possible to utilise electronic computing machines ‘to assess such pressures and tendencies over an area as vast as 1000 miles square, and to do it for various levels in the atmosphere. Millions of computations can be done in an hour or two, and several predictions last year were extremely encouraging, some strikingly so. Nothing can stop a hurricane in full swing, but it may eventually prove possible to modify local conditions ahead ot it in such a way as to divert its course, to lead it by the hand, ag it were, and so avert calamities that at present seem inevitable. Before we can expect proposals for breaking up the conditions likely to produce the birth of a hurricane, or for diverting a violent hurricane off its later course, there is a vast field of detailed knowledge to be acquired; but it is satisfying and exciting to know that at last a major attack on the whole prob-: lem is being made and, though we in New Zealand do not have a direct stake in the ultimate solutions, we can take a close interest in progress towards ameliorating this terrible scourge of Nature. —