PART I.

By the Hon.Ralph Abercromby, F. M. S., andWilliam Marriott, F. M. S., reprinted from the “Quarterly Journal of the Meteorological Society,” published in London.

The attempt to foretell the weather is not of recent date; the ancients carefully studied the sky and clouds, and endeavored to predict the kind of weather that was likely to ensue; and a number of the popular prognostics of the weather of his time are recorded by Aristotle in his workon meteors. In later times our forefathers studied the weather, and as they had no instruments to guide them they observed natural objects and noticed the appearances of the sky and clouds, and also the movements of animals, birds, plants, &c. Shepherds and sailors especially being exposed to all kinds of weather, would naturally be on the lookout for any signs of a coming change, and after a time would begin to associate certain appearances with certain kinds of weather. A good deal of weather wisdom of the above character has been thrown into proverbs, trite sayings, and popular verse; and we propose in the present paper to examine and explain some of these by the aid of the most recent discoveries of meteorological science. A great advance has been made in meteorology during the last twenty years, owing to the introduction of daily synoptic charts of the distribution of atmospheric pressure, temperature, wind, rain, &c. From these it is evident that there is a distinct relation existing between the distribution of pressure and the direction and force of the wind, and the temperature and weather generally. A glance at a number of the charts shows that there is nearly always present either an area of low pressure, called a cyclone, usually having an approximately circular form, and, as a rule, moving in an easterly or northeasterly direction; or an area of high pressure, called an anticyclone, also nearly circular in form, but almost stationary in position. The wind in all cases also blows in a direction nearly parallel with the isobars, having the region of lowest pressure on the left hand. This has given rise to the simple law propounded by Dr. Buy’s Ballot, for the northern hemisphere, viz: “Stand with your back to the wind, and the barometer will be lower on your left hand than on your right.” In cyclones the wind circulates in the opposite way to which the hands of a watch move, but exhibits usually a little in-draught; while in anticyclones the wind circulates in the same way as the hands of a watch, but exhibits usually a little outward motion. The intensity of the wind in all cases depends upon the closeness of the isobars; for the closer the isobars the greater is the difference in pressure in a given distance, and consequently the stronger the wind. Nearly all of our weather is of the cyclonic or anticyclonic type, and is entirely dependent upon the form and distribution of the isobars. It is, therefore, by the aid of isobaric charts that we shall attempt to explain popular prognostics, and to associate them with certain kinds of weather. The method of research actually adopted has been for many years past totake notes of any good observation of any prognostic and put them in a portfolio, with the nearest synoptic chart available, or preferably with the nearest, both before and after. When a sufficient number had been collected they were analyzed, and the remarkable result has been arrived at that the greater number of prognostics are simply descriptive of the weather and appearance of the sky, in the different portions of the various shapes of isobars seen on synoptic charts, and that they indicate foul or fair weather just as they precede the shifting areas of rain or blue sky which are mapped out by the isobaric lines. These charts not only show the success of the prognostics, but also explain wherein they sometimes fail, by tracing the changes of each particular condition of the weather. Hitherto the only prognostics which have been accounted for have been those due to excessive damp, but by means of isobaric charts many others can be readily explained. It must not be supposed that the modern methods diminish the value of prognostics, for even in forecasting weather from synoptic charts they are of great value, and are always exceedingly useful to solitary observers who have only a single barometer to depend upon besides these prognostics, as, for instance, on board ship.

We hope that the present paper will create an interest on the part of many in this subject, and show that it is within their power to assist in advancing the science of meteorology, so that it may not remain any longer in the unsatisfactory state set forth in the following old Bedfordshire lines:

“Well, Duncombe, how will be the weather?”“Sir, it looks cloudy altogether,And coming across our Houghton Green,I stopped and talked with old Frank Beane.While we stood there, sir, old Jan SwainWent by and said he knowed ’twould rain;The next that came was Master Hunt,And he declared he knew it wouldn’t.And then I met with Farmer Blow,He plainly said he didn’t know,So, sir, when doctors disagree,Who’s to decide it, you or me?”

“Well, Duncombe, how will be the weather?”

“Sir, it looks cloudy altogether,

And coming across our Houghton Green,

I stopped and talked with old Frank Beane.

While we stood there, sir, old Jan Swain

Went by and said he knowed ’twould rain;

The next that came was Master Hunt,

And he declared he knew it wouldn’t.

And then I met with Farmer Blow,

He plainly said he didn’t know,

So, sir, when doctors disagree,

Who’s to decide it, you or me?”

We shall first take a typical well formed cyclone. In the accompanying diagram (Fig. 1) the broad features of the relation of cloud and rain to a cyclone centre are shown, the full line indicating the path of the depression, and the dotted line at right angles to it is the trough or locus of the lowest reading of the barometer.

Fig. 1.—Weather in a Cyclone, November 14, 1875.

In the extreme front of the depression there is a blue sky, then, as the barometer begins to fall, and sometimes even before that takes place, a bank of cirro-stratus, preceded by a halo-bearing sky, makes its appearance, which gradually becomes lower and denser, and forms an overcast, dirty sky. In the whole front of the depression the temperature rises, and the atmosphere feels muggy and close. In the right-hand front the clouds assume the cumulo-stratus type, with driving rain later on. In the left-hand front the air is cooler, but still oppressive, with an easterly wind and overcast sky, succeeded by drizzling rain or ill-defined showers. When the trough of the depression has passed the barometer begins to rise, the wind changes and becomes squally, with showers of rain; the air grows cooler, and the clouds break and ultimately clear away.

Now, with regard to the prognostics with reference to Fig. 2, wherethe characteristic weather in the different portions of a depression are given in a diagrammatic form, it will be seen that the first indication of a coming change is the appearance of a halo round the sun or moon in the cirro-stratus clouds. Hence,

When round the moon there is a brugh,The weather will be cold and rough.

When round the moon there is a brugh,

The weather will be cold and rough.

The moon with a circle brings water in her beak.

Halos predict a storm (rain and wind or snow and wind) at no great distance, and the open side of the halo tells the quarter from which it may be expected.

Mock suns predict a more or less certain change of weather.

Fig. 2.—Cyclone Prognostics.

With regard to the open side of the halo indicating the quarter from which the storm may be expected, it does not appear that this can be much used as a prognostic. It, however, most probably originated in the fact that halos are often seen in the southwest or west, when the sun or moon is rather low, the lower portion of the halo being cut off by clouds banking up in that direction, and that our storms generally come from those quarters. As a specimen of the value of prognostics we give some details of halos. When rain does not fall within thirty-six hours, any subsequent rain probably belongs to a new depression.

During the six years ending June, 1882, one hundred and fifty-five solar halos and sixty-one lunar halos were observed in the neighborhood of London, and they occurred with the following winds:

After the halo comes the pale or watery sun and moon.

When the sun appears of a light, pale color or goes down in a bank of clouds, it indicates the approach or continuance of bad weather.

If the sun goes pale to bed,’Twill rain to-morrow, it is said.

If the sun goes pale to bed,

’Twill rain to-morrow, it is said.

A red sun has water in his eye.

When the moon has a white look or when her outline is not very clear, rain or snow is looked for.

From the extreme damp in this part of the depression, while the sky generally is pretty clear, cloud forms round and “caps” the tops of hills, a circumstance that has given rise to numerous local sayings:

When the clouds are upon the hills,They’ll come down by the mills.When Cheviot ye see put on his cap,Of rain ye’ll have a wee bit drap.If Riving Pike do wear a hood,Be sure the day will ne’er be good.When Bredon Hill puts on his hatYe man of the vale beware of that.

When the clouds are upon the hills,They’ll come down by the mills.

When the clouds are upon the hills,

They’ll come down by the mills.

When Cheviot ye see put on his cap,Of rain ye’ll have a wee bit drap.

When Cheviot ye see put on his cap,

Of rain ye’ll have a wee bit drap.

If Riving Pike do wear a hood,Be sure the day will ne’er be good.

If Riving Pike do wear a hood,

Be sure the day will ne’er be good.

When Bredon Hill puts on his hatYe man of the vale beware of that.

When Bredon Hill puts on his hat

Ye man of the vale beware of that.

From the same excessive damp the following may be explained:

When the walls are more than usually damp rain is expected.

Doors and windows are hard to shut in damp weather.

The sailor notes the tightening of the cordage on his ship as a sign of coming rain.

A lump of hemp acts as a good hygrometer, and prognosticates rain when it is damp.

When walls built of stones which have been quarried below high water mark become damp, wet weather is at hand.

Also, owing to excessive moisture, clouds appear soft and lowering, and reflect the glare of iron-works and the lights of large towns:

The glare of the distant Ayrshire iron-works being seen at night from Cumbræ or Rothsay, rain is expected next day.

In Kinkardine of Monteith (Perthshire) and in all that district the reflections from the clouds of the furnaces of the Devon and Carrow works (to the east) foretell rain next day.

Also:

When the flames of candles flare and snap or burn with an unsteady or dim light, rain, and frequently wind also, are found to follow.

This is especially applicable to oil-lamps or tallow candles.

As the depression approaches and the atmosphere becomes gloomy, close, and muggy, some people are troubled with rheumatic pains and neuralgia, old wounds, and corns are painful, animals and birds are restless, and drains and ditches give out an offensive smell:

When rheumatic people complain of more than ordinary pains in the joints, it will rain.

If corns, wounds, and sores itch or ache more than usual, rain is to fall shortly.

A coming storm your shooting corns presage,And aches will throb, your hollow tooth will rage.

A coming storm your shooting corns presage,

And aches will throb, your hollow tooth will rage.

When animals seek sheltered places instead of spreading over their usual range, an unfavorable change is probable.

Hark! I hear the asses bray,We shall have some rain to-day.

Hark! I hear the asses bray,

We shall have some rain to-day.

If oxen turn up their nostrils and sniff the air, or if they lick their fore feet, or lie on their right side, it will rain.

Goats leave the high grounds and seek shelter before a storm.

Hogs crying and running unquietly up and down with hay or litter in their mouths, foreshow a storm to be near at hand.

When birds of long flight—rooks, swallows, or others—hang about home and fly up and down, or low, rain or wind may be expected.

This tumbling of rooks is amongst the best known signs of rain in places where those birds are found.

When the peacock loudly bawls,Soon we’ll have both rain and squalls.

When the peacock loudly bawls,

Soon we’ll have both rain and squalls.

If toads come out of their holes in great numbers, rain will soon fall.

If glow-worms shine much, it will rain.

When gnats bite keenly, and when flies keep near the ground, we look for wind and rain.

When spider webs are seen floating about in the air, farmers regard it as a sign of coming rain.

When many bees enter the hive and none leave it, rain is near.

Also, from cloud and gloom, plants shut up their petals early:

TheConvolvulus arvensis(small bind-weed),Anagallis arvensis(scarlet pimpernel), andCalendula pluvialisshut up their flowers before approaching rain. (Thepimpernelhas been called the poor man’s weather-glass.)

Dr. Jenner’s well-known lines are very good, as they contain references to most of the natural prognostics. (See page110, General Prognostics.)

It will be seen, however, later on, that the sayings about the rainbow, distant hills, and whirling dust, though good prognostics, do not belong to a depression.

As the depression centre approaches still nearer, rain sets in and continues till the barometer turns to rise. The passage of the trough is often associated with a squall or heavy shower, commonly known as “a clearing shower.” Immediately the air becomes cooler and loses the former muggy sensation, and soon small patches of blue sky appear.

When as much blue sky is seen as will make a Dutchman a jacket (or a sailor breeches) the weather may be expected to clear up.

A small cloudless place in the northeast horizon is regarded both by seamen and landsmen as a certain precursor of fine weather or a clearing up.

The steady rain breaks up into showers or cold squalls, which are followed by hard detached cumulus or strato-cumulus till the sky becomes blue again:

When after a shower, the cirro-strati open up at the zenith, leaving broken or ragged edges pointing upwards, and settle down gloomily and compactly on the horizon, wind will follow, and will last for some time.

This is a description of a clearing up before the windy portion of a depression has passed.

In the south of the depression near the outskirts, windy cirrus and “mare’s tails” are observed, which indicate wind rather than rain, as they are south of the rainy portion.

The cloud called goat’s hair or the gray mare’s tails forebodes wind.

If clouds look as if scratched by a henGet ready to reef your topsails then.Mackerel sky and mare’s tails,Make lofty ships carry low sails.

If clouds look as if scratched by a henGet ready to reef your topsails then.

If clouds look as if scratched by a hen

Get ready to reef your topsails then.

Mackerel sky and mare’s tails,Make lofty ships carry low sails.

Mackerel sky and mare’s tails,

Make lofty ships carry low sails.

The shift of the wind is different in the right-hand portion of the depression to what it is in the left-hand portion. In the former, on its first approach, the wind backs to south and falls very light to an almost ominous calm. The first puffs or “paws” of wind give rise to a noise in tree tops without much wind, and little eddies of dust, or to a whistling of the wind indoors, which are all well-known signs of rain. Then, as the depression passes along, the wind gradually veers to southwest and west, with increasing strength. Hence,

When the wind veers against the sun,Trust it not, for back ’twill run.When the wind is in the southIt is in the rain’s mouth.

When the wind veers against the sun,Trust it not, for back ’twill run.

When the wind veers against the sun,

Trust it not, for back ’twill run.

When the wind is in the southIt is in the rain’s mouth.

When the wind is in the south

It is in the rain’s mouth.

In the left-hand side of the depression the wind will back right round from south through east to north and northwest. In the rear of the depression on the left-hand side the wind blows from the northeast and then north, when the clouds begin to break and the weather to clear. When the depression has nearly passed away the wind in the rear draws round to the northwest, and gradually abates, and the weather becomes fine. Hence the saying:

Do business with men when the wind is in the northwest.

This bringing the finest weather is said to improve men’s tempers, as opposed to the neuralgic and rheumatic sensations felt in front of a depression.

Though the bulk of British weather is made up of cyclones and anticyclones, there are two other distributions of pressure marked out by wedge-shaped isobars and straight isobars respectively, which have never before been described, but which are associated with many well-known sayings. The chief interest in these prognostics consists in the contrasts which they present to cyclone prognostics, as in many cases they are associated with fine or dry weather, as opposed to the damp of an approaching depression. We shall first describe the prognostics which characterize the wedge-shaped area of high pressure that is frequently formed between a retreating and an advancing depression, as it is by far the most common.

All these prognostics owe their value to the fact that as the new depression comes on, rain may be expected. By reference to Fig. 3 it will be seen that in the rear of the retreating depression the weather is beautifully fine, of the sort of which we should say that it was “too fine to last,” or, if it lasted a whole day, we should call it a “pet day.”

Fig. 3.—Wedge-sharped Isobars.

An unseasonably fine day in spring is called a pet day in Scotland. The fate of pets they say awaits it, and they look for bad weather on the morrow.

During the day the sun is burning hot:

When the sun burns more than usual, rain may be expected.

During the night white frost is formed, owing to calm radiation:

A white frost never lasts more than three days; a long frost is a black frost.

Frost suddenly following heavy rain seldom lasts long.

As the day advances after a white frost, the air becomes dull from the influence of the on-coming depression; whence the saying—

When the frost gets into the air it will rain.

During the very fine weather, on the east side of a wedge-shaped area there is often great visibility with a cloudless sky:

The further the sight the nearer the rain.

When the Isle of Wight is seen from Brighton or Worthing, rain may be expected.

When to the people about Arbrouth the Bell-Rock light is particularly brilliant, rain is expected.

About Cape Wrath and along that part of the coast when the Orkney Islands are distinctly seen, a storm or a continuation of bad weather is prognosticated.

When from Ardersier and the adjoining parish on the southeast side of the Moray Firth the distant Ross-shire hills are distinctly seen in the morning rain is expected that day.

To the people in Eaglesham, in Renfrewshire, when the Kilpatrick hills appear near a change to wet is looked for; but when they appear remote, dry weather will continue.

If the old moon embraces the new moon, stormy weather is foreboded.

Great confidence is placed in this old prognostic:

I saw the new moon late yestreenWi’ the old moon in her arm,And if we gang to sea, master,I fear we’ll come to harm.

I saw the new moon late yestreen

Wi’ the old moon in her arm,

And if we gang to sea, master,

I fear we’ll come to harm.

The reason of “visibility” is uncertain; the old idea that it is due to excess of vapor is certainly erroneous. The dry and wet bulb hygrometer always indicates a considerable amount of dryness when it is remarked, and Mr. Cruickshank has shown by long observation at Aberdeen that visibility is greatest at the driest season of the year.

At the extreme northwest edge of a depression there is often unusual “refraction,” a well-known sign of rain. This seems to be due to the cold air in the rear of a depression being much below the temperature of the sea. If so, it is a sign of rain, for the reason that one depression is usually followed soon by another, which also explains the saying—

A norwester is not long in debt to a souwester.

Refraction and visibility combined also explain the following curious local prognostic:

When Ailsa Craig is distinctly seen, and seems near at hand, the people of Cumbræ look for change. When the weather is going to be finer it lies flat; but when rain is coming it assumes the form of a mushroom.

Ailsa Craig is an isolated rock standing in the Firth of Clyde, about thirty miles from Cumbræ. It has a conical top, with precipitous sides, so that in ordinary weather only the top is seen lying flat on the horizon; but sometimes in the rear of a depression it appears lifted by refraction, and the light encroaches at the edges, as is often seen with projecting promontories, giving the whole a fanciful resemblance to a mushroom. The prognostic is mistrusted by the inhabitants during frost, and we have proved it by our own observation. On the west side of the wedge-shaped area, as the new depression comes on, the blue sky gradually assumes a dirty appearance, accompanied by a halo, and gathers into cloud, and later on rain begins to fall; while in the southern portion the rain is often preceded by strips of cirrus, either lying in the direction of the wind, or sometimes at right angles to it:

Cirrus at right angles to the wind is a sign of rain.

Now we come to the consideration of some very interesting rain prognostics associated with straight isobars. While those in a depression are preceded by an almost ominous calm, and a dirty, murky sky, these are associated with a hard sky and blustery wind, of which it would be ordinarily remarked “that the wind keeps down the rain,” or “that when the wind falls it will rain.” While also the prognostics which precede cyclone rain hold good for the reason that they are seen in front of the rainy portion, those associated with straight isobars hold good because, though there is little rain actually with them, the area which they cover to-day will probably be covered by a depression to-morrow—the conditions being favorable for the passage of depressions.

On turning to Fig. 4 it will be seen that while the pressure is high to the south, it is generally low to the north, without any definite cyclonic system, and that the isobars run straight nearly east and west.

Fig. 4.—Straight Isobar Prognostics.

Near the high pressure the sky is blue, then as we approach the low pressure feathery cirrus, or some form of windy sky, makes its appearance, while a blustery wind whirls the dust, or blows the soot down; and animals turn their tails to the wind to avoid its force on their faces:

When chimneys smoke and soot falls, bad weather is at hand. The whistling of the wind heard within doors denotes rain.

When sheep, cattle, or horses turn their backs to the wind, it is a sign of rain.

Getting still nearer the low pressure, the sky is found to be gathering into hard stratus, at first with chinks between its masses, through which divergent rays stream down under the sun, which is spoken of as “the sun drawing water.” Sometimes, especially in winter, these rays are lurid, and are referred to in the following prognostic:

Along the north shore of the Solway, from Dumfries to Gretna, a lurid appearance in the eastern or southeastern horizon, called from its direction “a Carlisle sky,” is thought a sure sign of coming rain. They describe it as lurid and yet yellowish, and the common saying is:

The Carle skyKeeps not the head dry.

The Carle sky

Keeps not the head dry.

At the same time there is often great “visibility” with a hard overcast sky, and moderately dry air, in which the stratus seems to play the part of a sunshade, for as soon as the sun comes out the clearness of distant objects diminishes. This visibility must not be confounded with the visibility already described with a cloudless sky, which occurs with wedge-shaped isobars. Simultaneously we often find “audibility.”

If the noise of a steamer or railway train is heard at a great distance, rain is predicted.

This distinctness of distant sounds must be carefully distinguished from sounds which are not usually heard, being brought up by the windcoming from a rainy quarter. For instance, the whistle of a railway train to the south of a house will not be usually heard with the normal southwest wind of this country; but when the wind backs in front of a depression to the south, then it will be heard, and although this will be a good prognostic, still it is not true audibility.

When people of Monzie (Perthshire) hear the sound of the waterfalls of Shaggie, or the roar of the distant Turret clearly and loudly, a storm is expected; but if the sound seems to recede from the ear till it is lost in the distance, and if the weather be thick a change to fair may be looked for speedily.

In Fortingall (Perthshire) if, in calm weather, the sound of the rapids on the Lyon is distinctly heard, and if the sound descends with the stream, rainy weather is at hand; but if the sound goes up the stream and dies away in the distance, it is an omen of continued dry weather, or a clearing up if previously thick.

The course of Turret and Lyon is from west to east.

True “audibility” is best described by the saying:

A good hearing day is a sign of wet.Much sound in the air is a sign of rain.

A good hearing day is a sign of wet.

Much sound in the air is a sign of rain.

This last exactly conveys the kind of sound referred to. The reason why audibility is produced is unknown, but the old idea that it is due to excessive moisture in the air is certainly erroneous; in several instances we have observed that the upper current of the wind appeared to be moving much faster than the lower, and perhaps that may have something to do with it. When the gradients are very steep, a little rain sometimes falls with straight isobars, generally in light showers, with a hard sky.

Though as a matter of convenience we have described the sequence of weather as we proceed from high to the low pressure, it must be clearly understood that it does not represent the sequence of weather to a single observer, but rather what the weather will be simultaneously in different parts of the country; for instance, that if there are cirrus clouds in London there may perhaps be a lurid sky in Edinburgh. The prognostic value of all is due to the fact that a depression will soon form which will probably extend over the whole country.

Having spoken of cyclones, we shall now direct our attention to anticyclones. In the daily weather charts we sometimes see but two or three isobars, and these are a considerable distance apart, and extend over a large area. The pressure is highest in the centre, and gradually diminishes outwards. The air is calm and cold in the central area, but on the outskirts the wind blows in the direction of the hands of a watch. These are the special features of an anticyclone. The weather in an anticyclone is almost the opposite of that in a depression; that in the latter being wet and unsettled, while that in the former is usually settled and fine, with more or less haze in the air. Another great difference is that while depressions are generally rapid in their movements, anticyclones are nearly stationary; and it is for this reason that they are associated with “settled” fine weather. In the area of high pressure the characteristic features are largely modified by what is termed “radiation” weather, as determined by diurnal and seasonal variations; and as the pressure is nearly stationary, these diurnal and seasonal variations are the chief features of anticyclonic weather.

We shall now give the prognostics due to the variations in some detail, Fig. 5. The sky being generally clear and the air calm, the temperature is high in the day and low at night. In summer brilliant sunshine prevails during the day, and at night there is heavy dew, and in low-lying places mist.

Heavy dews in hot weather indicate a continuance of fair weather, and no dew after a hot day foretells rain.

If mist rises in low ground and soon vanish, expect fair weather.

Thin, white, fleecy, broken mists, slowly ascending the sides of a mountain whose top is uncovered, predicts a fair day.

When the mist creeps up the hill,Fisher out and try your skill.

When the mist creeps up the hill,

Fisher out and try your skill.

When in the morning the dew is heavy and remains long on the grass, when the fog in the valleys is slowly dissipated and lingers on the hill-side, when the clouds seem to be taking a higher place, and when a few loose cirro-strati float gently along, serene weather may confidently be expected for the greater part of that day.

Fig. 5.—Anticyclone Prognostics.

These all refer to night radiation, mist being dispersed by the sun’s rays. Fine, light, genial weather raises the spirits and exerts an enlivening influence not only on human beings but also on animals, birds, insects, &c. Hence the saying:

If larks fly high and sing long, expect fine weather.

When sea birds fly out early and far to seaward, moderate winds and fair weather may be expected.

If rooks go far abroad it will be fine.

Cranes soaring aloft and quietly in the air foreshow fair weather.

If kites fly high, fine weather is at hand.

Wild geese, wild geese, ganging out to sea,Good weather it will be.

Wild geese, wild geese, ganging out to sea,

Good weather it will be.

When owls whoop much at night, expect fair weather.

Bats, or flying mice, coming out of their holes quickly after sunset and sporting in the open air premonstrates fair and calm weather.

Chickweed expands its leaves boldly and fully when fine weather is to follow.

In winter frost is generally prevalent in the central area of an anticyclone, accompanied frequently by fog, which is most dense in the neighborhood of large towns. This is all due to the radiation of calm weather.

White mist in winter indicates frost.

In the evenings of autumn and spring vapor arising from a river is regarded as a sure indication of coming frost.

This comes from the air being colder than the water.

When fires burn faster than usual, and with a blue flame, frosty weather may be expected.

This is caused by reduced temperature of the outer air making a better draught in the chimney.

In winter when the sound of the breakers on shore is unusually distinct, frost is indicated.

These last two prognostics are explained by the fact that the atmosphere is very dense and still in an anticyclone.

In those places where fog does not form the sky will often be clear at night, whence—

Clear moon,Frost soon.

Clear moon,

Frost soon.

In winter when the moon’s horns are sharp and well defined, frost is expected.

The wind in an anticyclone system blows in the direction of motion of the hands of a watch, but slightly outwards, and as the anticyclone is nearly always stationary, the wind blows from the same quarter for several days together.

When the wind turns from northeast to east and continues two days without rain, and does not turn south the third day, nor rain the third day, it is likely to continue northeast for eight or nine days, all fair, and then come to the south again.

If the wind is northeast three days without rain,Eight days will pass before south wind again.

If the wind is northeast three days without rain,

Eight days will pass before south wind again.

The wind is usually very light in force.

It is said to be a sign of continued good weather when the wind so changes during the day as to follow the sun.

If wind follows sun’s course, expect fair weather.

This “veering with the sun,” as it is called, is the ordinary diurnal variation of the wind, which in this country is very obvious with the shallow gradients of an anticyclone. At sea-side places in summer very often “the wind is in by day and out by night,” which is the equivalent of the land and sea breezes of the tropics. Like two preceding prognostics, it is only in anticyclones that local currents of air, probably due to unequal heating of sea and land, can override the general circulation of the atmosphere in this country.

Sometimes in winter, on the southern side of the anticyclone, bitter east winds, with a black-looking sky, will prevail for several days together, when it may be truly said:

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