WEATHER-FORECASTING
To foretell with any degree of certainty the state of the weather for
twenty-four hours is of immense advantage 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 were abundant. 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 delays
To 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 of the 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 11 A.M. forecast based on the 8 A.M. observations;
and also of the 8.30 P.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 Brueckner, 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 for three 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, 89
Adam's Peak, spectre, 89
Afterglow described, 62;
dust-particles to form, 64
Air, change of, 55;
clearness and dryness, 49;
devitalised, 52;
disease-germs in, 53;
thunder-clouds, 49
Aitken, Dr., afterglows, 67;
anti-cyclones, 97;
colour of water, 75;
condensing power of dust, 2;
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, 78
Ammonia and cloud formation, 36
Annie Laurie, 17
Anti-cyclones, forecasting by, 97;
formation, 97;
cause of influenza, 109
Aratus, forecasting by moon, 61
Ariel's song, 42
Aurora 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, 72
Bagillt, condensing lead fumes, 84
Ballachulish, sunsets, 64
Ballantine's song, 17
Barometer, indications, 10
Ben Nevis, dust-particles, 30;
instruments, 104;
meteorology, 102;
observations, 105;
rainfall, 103;
regret at stoppage of Observatory, 103
Blairgowrie, personal description of afterglow, 62
Blue sky, 74;
cause of, 75, 77
Borrowing days, 117
Brocken, spectre, 89;
personal description, 90;
Noah's Ark, 90
Brueckner, climatic oscillations, 122
Buchan, Dr., Aitken's radiation from snow, 86;
Ben Nevis, papers on, 103;
_Challenger_ Reports, 114;
cold of 1886, 86;
east winds, 94;
isobars, 115;
rainfall statistics, 100;
on forecasting, 121
Buchanan, Ben Nevis Observatory, 102;
great prevalence of fog, 106
Buddha's Lights, of Ceylon, 72
Burns, allusions to aurora, 71, 73
Byron, storm in Alps, 50
_Challenger_ Expedition, 114;
temperature, 115;
thunder-storms, 116;
winds, 116
Chambers on sun-spots and grain prices, 113
Change of air, 55;
Strathmore to Glenisla, 56
Charles II., fog and smoke, 80
Chlorine and cloud formation, 36
Christison and colour of water, 75
Chrystal on Aitken's radiation from snow, 86
Cirro-stratus cloud, mackerel-like, 39
Climate, _Challenger_ notes, 115;
cone-warnings, 120;
Gulf Stream, 111;
oscillations, 120;
rainfall, 111;
sun-spots on, 112;
wooded country on, 111
Clouds, 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, 35
Cone-warnings, 121
Continental winds, 98
Cyclones, 95;
formation of, 96, 98;
small natural, 98
Decay of clouds, 37;
in thin rain, 41;
process, 38;
ripple markings, 39
Dew, evidence of rising, 22;
experiments, 15, 16;
false dew, 17;
formation of, 13
Disease-germs in air, 53;
causes, 53;
deposited by rain, 55
Diseases, and east wind, 94;
personal notes, 95
Dumfries, dust in air at, 46
Dust, 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;
Hyeres, Mentone, Rigi Kulm, 29;
Lucerne, Kingairloch, 30;
when not necessary, 36
Dust enumeration, deductions on, 31
Earn, Loch, splash of drop at, 101
Earthshine, 59
Ehrenberg, on colour of water, 75
Evelyn, fumifugium, 80;
remedy for smoke, 82
Falkirk, Dr. Aitken's experiments on haze, 47
False dew, 19
Fitzroy on aurora as a foreboder, 73
Fog, counter, 31;
dry, 41;
formation, 24;
more in towns, 25;
and smoke, 80
Folk-lore, 50
Foreglow, described, 66;
how produced, 67
Fort William Observatory, 102
Frankland, disease-germs, 53
Franklin, lightning, 51
Gassendi, named aurora, 72
Gillespie, Dr., on weather and influenza, 107
Glasgow, fog, 81
Glass, appearing damp, 44
Glenisla, ozoned air, 56
Grain crops and sun-spots, 112;
Chambers' tables, 113
Great amazing light in the north, 72
Gulf Stream, effects on climate, 111
Gunpowder, great condensing power, 44
Haze, what is, 43;
how produced, 44;
in clearest air, 45;
stages of condensation, 46;
in sultry weather, 46;
dryness of air and visibility, 48
Health improved by change of air, 56
Highland air, few disease-germs, 55
Hoar-frost, frozen dew, 20;
on under surfaces, 21
Humboldt, isotherms, 114
Hydrogen peroxide and cloud formation, 36
Hyeres, dust-particles, 29
Indian Ocean, colour, 75
Influenza, weather and, 107;
six distinct epidemics, 108;
spread of anti-cyclonic conditions, 109
Isobars by Buchan, 115
Isotherms by Humboldt, 114
Italian lakes, stages of condensation, 45
Job, on dew formation, 13
Kelvin recorder, 84;
Aitken's radiation from snow, 86
Kew, instruments set, 121
Kingairloch, dust-particles, 30, 46
Kirchhoff, lower temperature of sun-spot, 112
Krakatoa, eruption of, dust-particles, 63
Le Verrier and weathercharts, 119
Lockyer, and sun-spots, 112
Lightning, electricity, 51;
photographed, 51;
sheet and forked, 51;
ozone, 52
Lodge, electrical deposition of smoke, 83
London, coals consumed, 25;
sulphur and fog, 25;
fog in reign of Charles II., 81;
Meteorological Office, 11, 120
Lord Derwentwater's Lights, 72
Lower animals, sensitiveness, 11
Lucerne, dust-particles, 30
MacLaren, Aitken's radiation from snow, 86
Magnesia, small affinity for water-vapour, 44
Man in the street, 11
Mediterranean, brilliant colour, 77
Mentone, dust-particles, 29
Merry Dancers of Shetland, 71
Meteors, producing dust, 37
Meteorological Council, London, 103;
Office, 120;
cone-warnings, 121;
regular forecasts, 123
Milne Home on Ben Nevis, 103
Milton, dust numberless, 26
Moon, old, in new moon's arms, 58;
weather indications, 59, 61
Mountain giants, 88;
Adam's Peak, 89;
Brocken, 89
Munich, International Meteorological Conference, 35
Murray, _Challenger_ Expedition, 114
Nardius, dew exhalation, 13
Newton, colour of sky, 77
Nimbus, cloud, 35
Oak and ash, on climate, 118
Ochils, one-coloured rainbow, 70
Pacific, colour, 75
Paris, aurora, 71;
disease-germs, 55
Paton, Waller, bronze tints in sunsets, 64
Piazzi Smith, aurora, 72
Picket, dew-formation, 14
Pilatus, fine rain, 42
Polar lightnings, 72
Radiant heat, producing fine rain, 41
Radiation from snow, 86
Rain, 98;
heavy rainfalls, 99
Rainbow, 68;
forecasts, 62, 69;
formation, 69;
one-coloured, 70
Rains, it always, 40;
radiant heat in process, 41;
Ariel's song, 43
Rankin, dust-particles, Ben Nevis, 30
Richardson, devitalised air, 51
Rigi Kulm, dust-particles, 29
Rolier, aurora, 73
St. Paul's, London, disease-germs in air, 54
Sanitary detective, 78
Shakespeare, tempest, 95
Shelley, old moon in new moon's arms, 59
Simoom and sirocco, 94
Skye, rainy, 40
Smoke, electrical deposition of, 83;
regenerators, 85
Smoking-room, condensing power, 44
Snow, bad conducting, 87;
radiation from, 86
Sodium dust, condensing power, 45
Spens, forebodings of moon, 61
Splash of a drop, experiments, 101
Stevenson, R. L., splash of drop, 101
Stewart, sun-spots, 112
Strachey on forecasts, 121
Strathmore, 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, 118
Strathpeffer, 9
Sulphur as a fog-former, 25
Sulphuretted hydrogen and cloud-formation, 36
Sunshine on cloud-formation, 35
Sun's spots, and aurora, 72, 112;
and grain crops, 112
Symons, rainfall, 100
Synoptic charts, 98
Tait, on Aitken's radiation from snow, 86
Tay Bridge, fall of, 92
Tennyson, aurora, 71;
dew, 19;
oak and ash, 119
Thermometer, indications, 10
Thomson, Wyville, _Challenger_ Expedition, 114
Thunder-storm described, 50
Valkyries, aurora, 73
Visibility, limit of, 48
Washington, Meteorological Office, 121
Water, pressure to show plant exudation, 18;
colour of, 75;
experiments on distilled, 76;
dust-particles vary colour, 77
Weather and influenza, 107
Weather-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', 123
Weather-lore, 50, 118
Weather talisman, 9;
call on barometer and thermometer, 10;
exceptional years, 117
Wells, Dr., on dew, 14
Wilson, Prof., on hoar-frost, 20
Wind, 92;
rates, 92;
trade, 93;
land and sea, 93
Woeikof, durability of cold, 88
Wordsworth, rainbow, 68
Worthington, splash of drop, 100
Wragge, observations at Ben Nevis, 104
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