WEATHER-FORECASTING
To foretell with any degree of certainty the state of the weather for twenty-four hours is of immenseadvantage to business men, tourists, fishermen, and many others. The weather is everybody’s business. And the probabilities of accurate forecasts are so improving that all are more or less giving attention to the morning meteorological reports.
Weather-forecasting depends on the principle from vast experience that, if one event happens, a second is likely to follow. According to the extent and accuracy of the data, will be the strength of the probability of correct forecasts. And the great end of popular meteorology is to demonstrate this.
We have given some explanations of the weather in some respects unique; and a careful consideration of these explanations will the more convince the reader of the importance of the subject. No doubt the changes of the weather are extremely complex, at times baffling; and the wonder is that forecasts come so near the truth.
For instance, the year 1903 almost defied the ordinary rules of weather, for it broke the record for rainfall. And, last year, so repulsive and unseasonable was the spring, that there seemed to be a virtual “withdrawal” of the season. I wrote on it as “The Recession of Spring.” Speak about Borrowing Days! We had the equinoctial gales of March about the middle of April. On very few days had we “clear shining to cheer us after rain,” for the bitter cold dried up any genial moisture. An old farmer remarked that “We’re gaun ower faur North.” No one could account for the backwardness of the season. Unless for the cheering songs of the grove-charmers, one would have forgotten the time of the year.
In March of this year, at Strathmore, the barometer fell from 30·5 inches (the highest for years) to 28·65 in five days without unfavourable weather following. It again rose to 30·05, then fell to 28·45, followed by a rise to 28·7 without any peculiar change. But in two days it fell to 28·4 (the lowest for years), followed by a deluge of rain and a perfect hurricane for several hours, while the temperature was fortunately mild. It was only evident at the end that this universal storm had been “brewing” some days before.
All are familiar with the ordinary prognostics of good and bad weather. A “broch” round the moon, in her troubled heaven, indicates a storm of rain or wind. When the dark crimson sun in the evening throws a brilliant bronzed light on the gables and dead leaves, we are sure that there is an intense radiation from the earth to form dew, or even hoar-frost.
According to the meteorological folk-lore, the weather of the summer season is indicated by the foliation of the oak and ash trees. If the oak comes first into leaf, the summer will be hot and dry, if the ash has the precedence it will be wet and cold. Looking over the observations of the budding of these two trees for half a century, I find that the weather-lore adage has been pretty correct. The ash was out before the oak a full month in the years 1816, ’17, ’21, ’23, ’28, ’29, ’30, ’38, ’40, ’45, ’50, and ’59; and the summer and autumn in these years were unfavourable. Again, the oak was out before the ash several weeks in the years 1818, ’19, ’20, ’22, ’24, ’25, ’26, ’27, ’33, ’34, ’35, ’36, ’37, ’42, ’46, ’54, ’68, and ’69; the summers during these years were dry and warm, and the harvests wereabundant. One can never think of this weather prognostic from nature without recalling the Swallow Song of Tennyson’s “Princess”:—
“Why lingereth she to clothe her heart with love,Delaying, as the tender ash delaysTo clothe herself, when all the woods are green?”
On a muggy morning a sudden clearness in the south “drowns the ploughman.” And yet enough blue in the sky “tae mak’ a pair o’ breeks” cheers one with the assurance of coming dry and sunny weather. The low flying of the swallows betokens rain, as well as any unseasonable dancing of midges in the evening. Sore corns on the feet, and rheumatism in the joints, are direful precursors. The leaves are all a-tremble before the approach of thunder. But throughout this volume I have given many illustrations.
But one of the largest and most important practical problems of meteorology is to ascertain the course which storms follow, and the causes by which that course is determined, so that a forecast may thereby be made, not only of the certain approach of a storm, but the particular direction and force of the storm. The method of conducting this large inquiry most effectively was devised by the French astronomer, Le Verrier—the great aspirant, with our own Couch Adams, for the discovery of the planet Neptune. He began to carry this out in 1858 by the daily publication of weather data, followed by a synchronous weather map, which showed graphically for the morning of the day of publication the atmospheric pressure and the direction and force ofthe wind, together with tables of temperature, rainfall, cloud, and sea disturbances from a large number of places in all parts of Europe. It is from similar maps that forecasts of storms are still framed, and suitable warnings issued; and a mass of information is being collected by telegraph from sixty stations in the British Islands, &c., of the state of the weather at eight o’clock every morning, and analysed and arranged at the Meteorological Office in London for the evening’s forecasts over the different districts of the country. A juster knowledge is being now acquired of those great atmospheric movements, and other changes, which form the groundwork of weather-forecasting.
The Meteorological Office, Westminster (entirely distinct from the Royal Meteorological Society), is administered by a Council (Chairman, Sir R. Strachey; Scottish member, Dr. Buchan), selected by the Royal Society. It employs a staff of over forty. The chief departments relate to: (1) Ocean Meteorology, including the collection, tabulation, and discussion of meteorological data from British ships, the preparation of ocean weather charts, and the issue of meteorological instruments to the Royal Navy and Mercantile Marine; (2) Weather Telegraphy, including the reception of telegrams thrice a day from selected stations for the preparation of the daily reports and weather forecasts. Representatives of newspapers, &c., receive copies of the 11A.M.forecast based on the 8A.M.observations; and also of the 8.30P.M.forecasts based on the observations received earlier in the day. In summer and autumn harvest forecasts are issued by telegraph to individuals who will defray the cost.The Office also collects climatological data from a number of voluntary and some subsidised stations. The “first order” stations include Valentia, Falmouth, Kew, and Aberdeen. These have self-recording instruments of high precision, giving a continuous record of the meteorological elements.
A Government Commission which sat last year, under the Rt. Hon. Sir Herbert Maxwell, Bart., have issued a Report, recommending a number of changes in the management and constitution of the Meteorological Office; and considerable modifications are not unlikely to take place in the near future. In his evidence before that Commission, the Chairman of the Council acknowledged that the great function of meteorologists is the collection of facts; but the interpretation of those collected facts, in a scientific manner, is still in a very immature condition. Dr. Buchan, in his evidence, confessed that forecasting by the Council is purely “by rule of thumb.” It is not possible to lay down hard and fast rules for forecasting.
With regard to the storm-warning telegrams, as a rule, the earliest trustworthy indication of the approach of a dangerous storm to the coasts of the British Isles precedes the storm by only a few hours. Delays are therefore very serious.
It is admitted by the best British meteorologists that the observations of the United States are better conducted, although the best instruments in the world are set and registered at Kew, in England. The work of weather forecasts and storm warnings is carried on with the highest degree of promptitude and efficiency at the Washington Central Office.This is because the work of predictions has been hitherto the chief work of the Office: the entire time of the observers, on whose telegraphic reports the forecasts are based, is controlled by the United States Weather Bureau; and the right of precedence in the use of wires is maintained.
Professor Brückner, of Berne, has devoted a lifetime to the comparatively new treatment of climatic oscillations, based upon observations made at 321 points on the earth’s surface, distributed as follows: Europe, 198; Asia, 39; N. America, 50; Cen. and S. America, 16; Australia, 12; Africa, 6. One of his conclusions is that an average time of about thirty-five years is found to intervene between one period of excess or deficiency of warmth and the next, accompanied by the opposite relative condition of moisture.
All are familiar with the hoisting of cone-warning as indication of a coming storm. This work is exceedingly important, especially for those connected with the sea by business or pleasure. On the known approach of a cyclone of dangerous intensity, special messages are sent from the London Meteorological Office, warning the coasts likely to be affected. When the cone is hoisted with its apex downwards, it means that strong south or south-west winds are to be looked for. When the cone is hoisted with its apex upwards, it indicates that strong winds from the north or north-east are expected. Of course they are merely useful precautions; but they are universally attended to by people on the sea-coast.
Though one may have reasonable doubts about the use that can be made of weather forecasts forthree days, such as are now regularly issued, on account of the finical, coy, spasmodic interludes on short notice, yet there is a wonderful certainty in the daily prognostics of the direction and strength of the wind, the temperature of the air, and the likelihood of rainy or fair weather, dependent on the broad uniformity of nature. This is very serviceable for people who have now to live at high pressure in business, in the enthralling days of keen competition. And it is a great boon to those who are in search of health by travelling, or who, in innocent pleasure, desire to live as much as possible in the open air. Very little credit is given to the “gas” of the isolated “weather prophet”; but those who have confidence in the usual weather forecasts from the Meteorological Office are satisfied in their belief; and those who, in self-confidence, ignore all weather prognostics, are still weak enough to read them and act up to them.
In practical meteorology, in the scientific explanation of popular weather-lore, and in the study of atmospheric phenomena, which so powerfully influence us, for gladness or discomfort, we may, as with other branches of science, even all our days, cheerfully go on in “the noiseless tenor of our way,”
“Nourishing a youth sublime,With the fairy tales of science and the long results of time.”
INDEX
Abercromby, spectre on Adam’s Peak,89Adam’s Peak, spectre,89Afterglow described,62;dust-particles to form,64Air, change of,55;clearness and dryness,49;devitalised,52;disease-germs in,53;thunder-clouds,49Aitken, Dr., afterglows,67;anti-cyclones,97;colour of water,75;condensing power of dust,43;decay of clouds,39;dew-formation,14;dust and atmospheric phenomena,29;electrical deposition of smoke,83;false dew,18;fog-counter,82;foreglows,67;formation of clouds,35;haze,44;hazing effects of atmospheric dust,47;Kingairloch experiments,30;one-coloured rainbow,70;radiation from snow,86;regenerators,85;sanitary detective,78Ammonia and cloud formation,36Annie Laurie,17Anti-cyclones, forecasting by,97;formation,97;cause of influenza,109Aratus, forecasting by moon,61Ariel’s song,42Aurora Borealis,71;forebodings,71-73;name by Gassendi,72;other names,72;safety valve of electricity,72;sun’s spots,72;sun control,74;symptoms,72Bagillt, condensing lead fumes,84Ballachulish, sunsets,64Ballantine’s song,17Barometer, indications,10Ben Nevis, dust-particles,30;instruments,104;meteorology,102;observations,105;rainfall,103;regret at stoppage of Observatory,103Blairgowrie, personal description of afterglow,62Blue sky,74;cause of,75,77Borrowing days,117Brocken, spectre,89;personal description,90;Noah’s Ark,90Brückner, climatic oscillations,122Buchan, Dr., Aitken’s radiation from snow,86;Ben Nevis, papers on,103;ChallengerReports,114;cold of 1886,86;east winds,94;isobars,115;rainfall statistics,100;on forecasting,121Buchanan, Ben Nevis Observatory,102;great prevalence of fog,106Buddha’s Lights, of Ceylon,72Burns, allusions to aurora,71,73Byron, storm in Alps,50ChallengerExpedition,114;temperature,115;thunder-storms,116;winds,116Chambers on sun-spots and grain prices,113Change of air,55;Strathmore to Glenisla,56Charles II., fog and smoke,80Chlorine and cloud formation,36Christison and colour of water,75Chrystal on Aitken’s radiation from snow,86Cirro-stratus cloud, mackerel-like,39Climate,Challengernotes,115;cone-warnings,120;Gulf Stream,111;oscillations,120;rainfall,111;sun-spots on,112;wooded country on,111Clouds, decay of,37;distances of,35;dry,42;even without dust,36;formation of,34;height of,34;numbering of cloud-particles,34;sunshine on cloud formation,35;varieties of,35Cone-warnings,121Continental winds,98Cyclones,95;formation of,96,98;small natural,98Decay of clouds,37;in thin rain,41;process,38;ripple markings,39Dew, evidence of rising,22;experiments,15,16;false dew,17;formation of,13Disease-germs in air,53;causes,53;deposited by rain,55Diseases, and east wind,94;personal notes,95Dumfries, dust in air at,46Dust, condensing power,43;from meteors,37;generally necessary for cloud formation,26;hazing effects,47;numbering,26;instruments for numbering,27;produces afterglows,64;produces foreglows,67;quantity in Bunsen flame,28;at Ben Nevis,30;Hyères, Mentone, Rigi Kulm,29;Lucerne, Kingairloch,30;when not necessary,36Dust enumeration, deductions on,31Earn, Loch, splash of drop at,101Earthshine,59Ehrenberg, on colour of water,75Evelyn, fumifugium,80;remedy for smoke,82Falkirk, Dr. Aitken’s experiments on haze,47False dew,19Fitzroy on aurora as a foreboder,73Fog, counter,31;dry,41;formation,24;more in towns,25;and smoke,80Folk-lore,50Foreglow, described,66;how produced,67Fort William Observatory,102Frankland, disease-germs,53Franklin, lightning,51Gassendi, named aurora,72Gillespie, Dr., on weather and influenza,107Glasgow, fog,81Glass, appearing damp,44Glenisla, ozoned air,56Grain crops and sun-spots,112;Chambers’ tables,113Great amazing light in the north,72Gulf Stream, effects on climate,111Gunpowder, great condensing power,44Haze, what is,43;how produced,44;in clearest air,45;stages of condensation,46;in sultry weather,46;dryness of air and visibility,48Health improved by change of air,56Highland air, few disease-germs,55Hoar-frost, frozen dew,20;on under surfaces,21Humboldt, isotherms,114Hydrogen peroxide and cloud formation,36Hyères, dust-particles,29Indian Ocean, colour,75Influenza, weather and,107;six distinct epidemics,108;spread of anti-cyclonic conditions,109Isobars by Buchan,115Isotherms by Humboldt,114Italian lakes, stages of condensation,45Job, on dew formation,13Kelvin recorder,84;Aitken’s radiation from snow,86Kew, instruments set,121Kingairloch, dust-particles,30,46Kirchhoff, lower temperature of sun-spot,112Krakatoa, eruption of, dust-particles,63Le Verrier and weathercharts,119Lockyer, and sun-spots,112Lightning, electricity,51;photographed,51;sheet and forked,51;ozone,52Lodge, electrical deposition of smoke,83London, coals consumed,25;sulphur and fog,25;fog in reign of Charles II.,81;Meteorological Office,11,120Lord Derwentwater’s Lights,72Lower animals, sensitiveness,11Lucerne, dust-particles,30MacLaren, Aitken’s radiation from snow,86Magnesia, small affinity for water-vapour,44Man in the street,11Mediterranean, brilliant colour,77Mentone, dust-particles,29Merry Dancers of Shetland,71Meteors, producing dust,37Meteorological Council, London,103;Office,120;cone-warnings,121;regular forecasts,123Milne Home on Ben Nevis,103Milton, dust numberless,26Moon, old, in new moon’s arms,58;weather indications,59,61Mountain giants,88;Adam’s Peak,89;Brocken,89Munich, International Meteorological Conference,35Murray,ChallengerExpedition,114Nardius, dew exhalation,13Newton, colour of sky,77Nimbus, cloud,35Oak and ash, on climate,118Ochils, one-coloured rainbow,70Pacific, colour,75Paris, aurora,71;disease-germs,55Paton, Waller, bronze tints in sunsets,64Piazzi Smith, aurora,72Picket, dew-formation,14Pilatus, fine rain,42Polar lightnings,72Radiant heat, producing fine rain,41Radiation from snow,86Rain,98;heavy rainfalls,99Rainbow,68;forecasts,62,69;formation,69;one-coloured,70Rains, it always,40;radiant heat in process,41;Ariel’s song,43Rankin, dust-particles, Ben Nevis,30Richardson, devitalised air,51Rigi Kulm, dust-particles,29Rolier, aurora,73St. Paul’s, London, disease-germs in air,54Sanitary detective,78Shakespeare, tempest,95Shelley, old moon in new moon’s arms,59Simoom and sirocco,94Skye, rainy,40Smoke, electrical deposition of,83;regenerators,85Smoking-room, condensing power,44Snow, bad conducting,87;radiation from,86Sodium dust, condensing power,45Spens, forebodings of moon,61Splash of a drop, experiments,101Stevenson, R. L., splash of drop,101Stewart, sun-spots,112Strachey on forecasts,121Strathmore, observations on hoar-frost,22;on decay of clouds,38;to Glenisla, change of air,56;observations on old moon in new moon’s arms,59;afterglow described,62;foreglow,66;cold of 1886,86;healthy by woods,111;observations on barometer,118Strathpeffer,9Sulphur as a fog-former,25Sulphuretted hydrogen and cloud-formation,36Sunshine on cloud-formation,35Sun’s spots, and aurora,72,112;and grain crops,112Symons, rainfall,100Synoptic charts,98Tait, on Aitken’s radiation from snow,86Tay Bridge, fall of,92Tennyson, aurora,71;dew,19;oak and ash,119Thermometer, indications,10Thomson, Wyville,ChallengerExpedition,114Thunder-storm described,50Valkyries, aurora,73Visibility, limit of,48Washington, Meteorological Office,121Water, pressure to show plant exudation,18;colour of,75;experiments on distilled,76;dust-particles vary colour,77Weather and influenza,107Weather-forecasting,116;advantages,117;principle,117;examples,118;old moon in new moon’s arms,59;by moon,61;oak and ash,118;cone-warnings,122;three days’,123Weather-lore,50,118Weather talisman,9;call on barometer and thermometer,10;exceptional years,117Wells, Dr., on dew,14Wilson, Prof., on hoar-frost,20Wind,92;rates,92;trade,93;land and sea,93Wœikof, durability of cold,88Wordsworth, rainbow,68Worthington, splash of drop,100Wragge, observations at Ben Nevis,104
Printed byBallantyne, Hanson & Co.Edinburgh & London