THE WHY OF THE WEATHER.

Oamaru Mail, Volume XXXVIII, Issue 10570, 27 September 1910, Page 2

THE WHY OF THE WEATHER.

SOME POPULAR FALLACIES r CORRECTED. ■ - * (By a Meteorologist.) 1 The extraordinary fact is that while * the most ridiculous theories are com- s placently accepted in circles intelligent 1 in every other respect, meterologists > the world over were never in such general agreement as to general causes, ( and it is especially unfortunate, therefore, that while the science of meteorology is assuming somewhat ol the exactness and surety of the sister sciences, the general public should with avidity take up the very latest "moon- . shiue-rrom-cucumbcr" suggestion and accept it as gospel truth. Just now, for instance, people in France and England are becoming ex-, cited over the explanation given out as positively new, original, and startling by Gam'ille Flammariou and bis followers, that the weather of Western Europe is brewed in the United States, and that the recent cold and wet spells in France and England are a direct result of the prevalence of hot waves on the North American Continent. All this has been set out with much pomp and circumstance of cabling back and forth to America, with the publication of much newspaper comment, lorcign | and Eii'dish. which would seem to indicate that the new theory was a contribution of weight which called out for a suspension of judgment on account of its great and momentous noveltv. . Now, sometimes even scientific patience ceases to be a virtue, though tne admirable British restraint ol the Meteorological OHice enables it to survive another Hurry of flighty soioneo without even taking time to explain the explanation. Since, however, ro manv People are taking the latest Flammarion theory seriously it seems to me that it is time to say that what- ■ ever was se'eminglv novel in it, that is, . the eastward drift of weather, is not new at all. while the further develop- ■ ment of this supposed novel theory s into an exact and reciprocal relation- • shin between the hot waves ol the ' United States and the cold, wet sumi mer of the European Continent, is simply mis-stating a condition well unilerI stood bv any American or Kuropeau - meteorologist of any standing. 1 The real gist of the weather suiia- - lion is this, "and it should reassure any - Ftoneh or' English citizen who tears 5 -,iiv American invasion other than that > of' dollars-.—lst: It is eternally true 5 that all the weather movements in the - Northern Hemisphere north ot the - Tropics come from West to East; 2nd: > That in the North Alantic Basin speci- " | ficallv he hot wave's in the United ■> j States and the wet weather in France

are the result of the very same predisposing cause. This predisposing cause, which in the United Slates m. nife'Sis itself in the form of a hot wave and in these latitudes iit the form of the prevailing moisture-laden oceanic winds, is the very familiar tropical high pressure area, or, as >t is called in the terminology ot the meteorologists, the Atlantic _ anticyclone. The hot wave in the United States. therefore. does not cause directly or indirectly a contrasting state of weather in Western Europe, since it is itself an effect of the general condition. but the abnormal weather there and here—hot and moist, and cold and wet —is simply due to the persistence of high pressures in the sub-tropical belts of the Gull Stales and the Mid-Atlantic. So long as these pressures continue hi'di in the Gulf States and over the Ulantie from the Bay of Charleston to Spain, so long will there be set. up over the "United States the deadly south-to-north aerial circulation which i.s always the factor and feature of the American hot wave. And so long as these high pressures tend to become "fixed," "as the phrase goes, to the South of England and central oyer the Azores with more or less excessive seasonal pressures, so long will this belt of high pressure—the Atlantic anticyclone—cause westerly winds over Western Europe with all the- con-s-queiices noted this year anil last, as the- moisture-laden winds retch region* favorable lor condensation. Moreover, when, as so often hap-

pens, these Atlantic high pressures which are great aerial \ortie-os wit! downward and outward motion, show "htle oscillation in their centre- (as hie b'-en true recently, as revealed in the splendid hydrographic charts of the Meteorological Office for the week ol June 30 to July 0) they also tend te hold up the- mere brisk easterly movement of the great travelling eddie; (cyclones and anti-cyclones) anel prevent those' variations in weathei changes which give variety anel reliei from a too long r-eign of either wel

weather eir of hot waves. Now. one of the most fascinating chapters of meteorology is that which reveals the globe as surrounded by an envelope of air. everywhere acting anel re-aciing. so that there is no part of the' glebe that i.s not. in direct relation with either portions: ami, partie-ularh in Ihe Northern Hemisphere, there is nothing so absorbing as the study of the great circum-poiar swirl from

West in Kast from A sili lei i lie Pacific-. :i!i(l from the Pacific- in Ihe North American ("mil ineiii in ihe Atlantic, ami I'i-chii ilie Atlantic lo Europe, ami so on aronml. Ami it is the changes in the path ol' this groat swirl, the variations in the aeri->l flow lines that bring about those variations in climate ami in weather from year to year which seem so inexplicable. Moreover, the changes in the paths ami the character of this swirl, whether sluggish or more, rapid, or mere northerly or more southerly, are determined entirely by iiie varying pressures ol' the groat subtropical rings of high pressure-. All this is true of the South temperate zone and of the tropical interdependence: for instance, of Australia and India and the South African Seas and the Arabian Seas, as Douglas Archibald and other .Hritish meteorologists have long since pointed out. What meteorologists of to-day are therefore engaged jn clearing up is not the connection between the weather all round the globe (since this is revealed every day in the synoptic charts of the whole Northern Hemisphere prepared by the United States Weather Bureau and in this country's weekly charts as well as in the German and French publications), but in finding out the cause of those yearly variations of pressure, which are of such importance to the great civilised nations that live in the Northern Hemisphere, and whose crops and business arc affected by the extremes which are possible in any given year, as we all know to our glliof. And it is to such problems that men like Lockyer and the United States specialists under Willis L. Moore have devoted and are devoting their attention. Unfortunately, so far as the public is concerned, the question as regards the weather from the North Atlantic is much confused with erroneous popular theories and ignorant folk beliefs, and particularly with one delusion that the familiar and altogether too famous Gulf Stream is the cause of every weather change, and it is because of this confusion, despite the facts available to any student, that the last suggestion of Flammarion is apt to confirm popular error and make a needless mystery of European weather changes. Even to-day in England and America, and especially among those who travel on the high seas, there is nothing that is referred to with such complacent acceptance as the idea that the Gulf Stream, per so, gives England its climate, as well as doing a thousand and one -wonderful things in America and the open Atlantic. The careful work of Professcr H. N. Dickson, of Oxford, of other weather specialists and of all modern physicists, is of no avail against this opinion, and it will room heresy to most to say that the Gulf Stream in itself has no more effect on the climate of England than the weather vane of St. Clement Danes : nor indeed have the hot waves in the United States any such immediate ind pacific effect as has just been suggested 'in France. England will continue to have a climate at times of the '-unvexed Bermoothes," and the United States its hot waves so long as the Atlantic high pressures maintain their position which they have had for thousands pud thousands of "years.

The actually new thing in meteorology is tli'" fact that world-wide conditions pro beinp; minded up every day by means of cable, land lines, and wireless telegraphy, and that we are on the eve of a great international development

of forecasting, which will be of inestimable value to such countries as England France, which lie in this great Eastward swirl of the North temperate zone circulation. And the newest, fact of all is that the variations in this swirl are not due to local conditions in the United.States and elsewhere, but to variations in the sub-tropical pressures, and these variations, as Lockyer lias pointed out, are not due to local conditions on the earth itself, but to yearly and _ long-range changes in the solar radiation.