How The Weather is Made

John Holt November 1 1912

How The Weather is Made

John Holt November 1 1912

How The Weather is Made

John Holt

While the actual making of the weather may still be beyond the limit of human control, the task of forecasting it has been reduced to a science. When in your daily paper you casually glance at the “probs.,” do you ever ask yourself how the forecasts are prepared? So far as Canada is concerned this article answers the question in all its details, explaining to the reader precisely “How the Weather is Made.” To most people the facts presented will prove of much interest, since so little is actually known of the operations of the much abused “weather man,” who after all simply does his best, which, as our contributor remarks, “is a mighty good one even if it is not perfect.”

“It’s talking ’bout the weather That has made the weather vain. “WHEN Providence made the weather,” said the dear old lady, “there was some dependin’ on it. But now these here meteorolologists have got aholt of it there’s no tellin’ what to expect.” Prom most of us the poor “weather man” gets short shrift. If we do not exactly blame him for the weather we get, we still cherish a sort of unspoken grudge against him as one who is connected intimately with the vile thing; and we jeer at him mercilessly when his forecasts happen to get left at the post instead of romping in winners at long odds. Poor “Probs.” has almost as few

friends as the Tax Collector. But he does his best — and a wonderfully good best _ it is if we only stopped to realize it. Not much more than a generation ago the weather man was still in the kindergarten stage of his business; three generations ago and there was no chance of his existing at all. Curiously enough it is electricity, one of the things he understands least about, and which occasionally is a distinct upsetter of his calculations, that has made possible a great deal of the work he does.

Until it was possible to get telegraphic reports of weather conditions from distant parts of the country, most weather work was necessarily of a

“post mortem” nature. All the weather man could do was to say what had happened on the previous day or make a guess at what would happen on the day after based on what had happened before under similar circumstances. Now he “sees the weather coming,” and tells you what he sees.

There has been a noticeable improvement in the “Probs.” of Great Britain within the past six or eight years. That is to say since the lengthening of the range of wireless telegraphy and its almost universal adoption on board ship. The forecasts were pretty good before, but with the aid of wireless reports— which are still rather scrappy and unorganized—the weather man has been able to correct and add to them the information he gets from the Atlantic— where a lot of English weather is manufactured. Atmospheric conditions which were quite unknown until they touched the cliffs of Galway, or came whooping over the Cornish moors at Land’s End, can nowadays be “seen coming” hundreds of miles away. And the Atlantic wireless reports are continually being improved.

CANADIAN WEATHER IMPROVEMENTS.

The next three or four years may see a similar improvement in the Canadian ■weather man’s work. There is talk of establishing a chain of wireless stations round Hudson Bay and through the trackless wastes of Labrador. At present all sorts of diabolical weather plots are secretly hatched in those forsaken regions of which the weather man can know nothing until they are right on top of him. Pie can make a rough sort of estimate of what to expect, but certainty is as yet denied him. It is as if he was compelled to keep the blinds pulled down over the north windows of his observatory—he can see weather coming from the east and the west and the south and is able to foretell pretty accurately what will be produced at any given point at any time by the conditions in these quarters of the compass; but the north is sealed and secret and at any moment something that the weather imps have been concocting behind the barrier of the arctic circle

may come swooping along and upset the whole bag of tricks. The matter will probably come under discussion at the present sitting of Parliament, and

if the Naval Department get their wireless stations established the weather man will be able to get his north window open and the occasions will be lessened on which we take our raincoats from the hook and mutter bitterly :

“Probs. said ‘Bright sunshine and continuing fair’ — and now look at the darned thing!”

However, as I say, the weather man’s best is a mighty good one even if it is not perfect. The difficulties under which he labors are enormous. His knowledge is great, but there are still wide gaps in it which he can fill only by guesswork. If we merely take a glance at what is the outside edge of a small portion of the weather man’s work we may realize something of the difficulties under which he labors and acquire more patience with his occasional failings.

All the weather of Canada and Newfoundland—which climatically are in confederation—pays a daily call at a not particularly conspicuous building on Bloor Street, Toronto. Most of the United States weather drops in there also, for the elections of last year had no climatic effect and there is perfect reciprocity in this commodity. And besides this there are less important calls from most of the weather all over the world. Terrible storms, cyclones, earthquakes rage—telegraphically—in that quiet building and the weather • man keeps an eye on them all and records their life history by drawing lines on maps.

The Toronto building is the central office of the meteorological service of Canada, corresponding to the head office of the United States Weather Bureau at Washington and the Central Office of London. It is the place where the “weather is made” for the whole Dominion—except the coastal strip on the other side of the Rockies — and for Newfoundland a s well. It is a big job even determining the “Probs.” and that is only a small portion of the weather man’s work.

To begin with it is necessary to realize that the weather man does things on a large scale — a very large scale. It is never a mere local affair, but an organization—for want of a better word —which does business continentally. The weather may stand with one foot in Algoma and the other in Texas and reach over and tickle the Atlantic coast with its hands, so to speak. _ And Probs. has to figure out what will be the precise effect on every part of Canada when the Texas foot is shifted and moved up to the middle west or over to San Francisco. What is more, he must try to foresee at what precise moment the foot will be shifted and_ the^ mood which will influence the direction of the shift.

The ’weather is, as it were, a giant, or a family of erratic giants. The weather man has studied their habits and can foretell their movements accordingly. Occasionally one of them changes his mind in a manner con-

trary to habit—shifts liis course, suddenly decides to sit down and enjoy the scenery at one particular spot, comes into unexpected collision with a brother giant and has a stormy argument, or gives a brother the cut direct whom the weather man has expected him to meet. But as a rule the weather man, through patient observation, can see what is going to happen, just as a keen observer of character and human nature can foretell with fair accuracy the actions of a human being.

Weather conditions depend upon the progression of “atmospheric disturbances” across the face of the world. All sorts of things give rise to and influence these disturbances and have an effect on their progression—mountain ranges, large bodies of water, even the wooded or cleared nature of tracts of country, and in addition there are minor local conditions which produce minor local effects without appreciably influencing the big areas of disturbance.

In dealing with these atmospheric

disturbances the meteorologist makes use of several “tools.” First and most important is the Barometer which takes note of the differences in the distribution of the atmosphere—which may be said, in fact, to determine the character of the atmospheric disturbances. Without the Barometer the weather man would be practically helpless. Then there are the Wind Vanes and Anemometers, for determining the direction and velocity of air currents; Thermometers for temperature; and Rain (bauges for recording the quantity of rainfall.

These are all very different from the ordinary variations of these instruments with which most people are familiar. The Barometer is a vastly more complicated affair than that frying-pan sort of thing which hangs in the front hall and which Pa taps with his finger and looks at wisely without really understanding anything of what it is trying to say. The Weather Vanes run on delicate bearings; the Thermometers

are tested to the last degree of accuracy ; the instruments are very carefully placed so that they will not be influenced by adverse circumstances; and all of them automatically record their movements during the twenty-four hours.

This is at the Toronto station. Across the continent are a chain of forty or more big sub-stations where the instruments are accurate but not necessarily so elaborate as in Toronto; and besides these there are innumerable small observation points scattered all over the country in, almost every town and village. People are sometimes surprised at the absence of snow guages as well as rain guages, but as a matter of fact they are of little use in a country with so heavy a snowfall as Canada; they get clogged and choked, or the snow blows out of them, and consequently the weather man has to fall back upon primitive measurements with a ruler at spots which he judges are representative, and can only regret the consequent loss of accuracy.

As a matter of fact even the most delicate instruments are not absolutely accurate. Take an Anemometer, for instance, a device consisting outwardly of four little cups at the ends of four horizontal arms which in their revolutions actuate a mechanism which indicates the velocity of the wind which turns them. Obviously when a gust of wind arises it must overcome a certain inertia in the instrument and there must be a small but appreciable delay before the arms start revolving. Conversely, when the gust dies down the anemometer must continue to spin for a moment before it also stops. Similarly the sluggishness of a thermometer must take a certain time to overcome before it responds to a change of temperature. With delicate instruments and various ingenious compensating devices these inaccuracies are reduced to a minimum and anyway they are far too small to have any effect on the comparatively rough work of “Probs.” I mention them and the snow guages merely as an indication of the mechanical difficulties which the weather man has to face in all branches of his work ; the laborious

calculations necessary to allow for these inaccuracies may well be imagined.

WORK IS EXTENSIVE.

Forecasting, as I say, is only one detail of the weather man’s work—an important detail but by no means the most difficult or complicated. There is much recording and tabulating to be done, and some research work. Mariners’ charts and bulletins detailing the recent weather in various parts of Canada have to be prepared and sent out; and there are certain special branches of the forecasting work to be attended to, such as wiring the various coastal stations to hoist storm signals and the like.

Take this “Notice to Mariners” for instance. “To Mariners:—In September during the past 39 years 1873 to 1911 each inclusive, 98 gales occurred on the Lakes, 28 fresh to heavy and 70 moderate. On 3 occasions the winds backed, 86 veered, and 9 they veered in some localities and backed in others. In the St. Lawrence Valiev and the Gulf there were 107 gales, 32 fresh to heavy and 75 moderate, 13 backed, 83 veered, and 11 backed in some localities and veered in others. In the Maritime Provinces 76 gales occurred,'21 fresh to heavy and 55 moderate, 10 backed, 58 veered, and 8 backed in some localities and veered in others.”

You see it is a digest of weather conditions over a period of forty years, and the records covering that period had to be searched in order to make it. Such searching and keeping up to date of the records is a detail of the weather man’s work.

But there is work enough even behind the ordinary little quarter column of small type we are familiar with in the morning’s paper and which ranks in importance in our eyes above the news of the Presidential elections, or the special correspondence from the European capitals. Directly and indirectly, some hundreds of people are concerned in building up the basis on which those half dozen slender little paragraphs are built.

Strung across the Dominion are the chain of observation stations. Victoria, Edmonton, Moose Jaw, Quebec, St.

John’s, Newfoundland, and Halifax are the chief sub-stations of the forty and odd which are in constant communication with “Probs.” at his Toronto headquarters. He has a sort of suburban residence at Victoria also, whence forecasts are issued of the weather along the Pacific slope. But all the rest of the Canadian forecasts come from Bloor Street.

At precisely the same instant, twice every twenty-four hours, observations are taken at all the stations. Thev are taken at 8 a.m. and 8 p.m. 75th meridian, which means of course, that they have to be taken later than that at points east of Toronto and earlier at points west owing to the difference of time. Thus the Dawson City man has to turn out at the cold grey hour of four in the morning to inspect his instruments, while the St. John’s weather man can take a comfortable breakfast before making his observations at nine.

The smaller sub-stations submit monthly reports which are used in the record and tabulation work. Sometimes their work is hardly scientifically accurate. I remember one meteorological sub-officer who got into a tangle with his own instruments. Although it was an exceptionally wet summer his rain gauge declared vehemently that there was a drought. The instrument was examined and found faultless, yet still the drought continued. Eventually, it was found that the officer’s small daughter, to save herself a trip to the pump, had been filling her watering pot at the gauge when she attended to the flowers in the greenhouse.

But occurrences like this do not happen where it is really important. You must imagine the various officers at various local hours of the day and night, but always at eight o’clock by Toronto time, going out and collecting the material for their reports. They take the barometric pressure of the atmosphere; the temperature of the air; make a note of the state of the weather—whether it is raining, snowing, clear or cloudy and so on ; note the direction and velocity of the wind; and the amount of precipitation since the previous reading; also if

in the morning, the lowest temperature of the preceding night, if at night, the highest of the preceding clay. The barometric readings they reduce to sea level, that is to say they make allowance for the height of the station above the sea and quote their readings as if taken at the sea level ; this is in order to make them comparable.

All these observations are then telegraphed through to the Chief at Toronto, and form the chief basis of his calculations. Besides these, however, he gets similar reports from various stations in the States, also twice a day ; and once a day from the whole northern hemisphere. Altogether he receives two hundred or more reports every day; about forty from points in Canada, 140 from the States, and 20 from Europe and Asia. Thus the weather man on Bloor Street, not only has a bird’s eye view of the weather all over Canada, but all across Asia and Russia and Europe—over the whole world, in fact, north of the equator.

When the observations are all in, the Chief hr.s to see how they fit in with one another, and from them deduce his various forecasts. How many maps of North America he has drawm in his time it is impossible to say, but he has drawn so many and is so familiar with the map that he can make one from memory any day and could probably come pretty close to accuracy blindfolded. The first step of his dav’s work is to take a map of North America and enter on it the various barometric readings he has received. Each of the stations has a barometric figure entered on it, and eventually those stations having the same figures are connected by lines called isobars. Isobars are drawn for every tenth of an inch difference in pressure, and it follows, of course, that all places along them, between the stations they connect have approximately the same barometric pressure. Arrows are drawn to show the wind direction and velocity at the various stations, and various symbols indicate the states of the weather. When the pressures and isobars have been filled in, the map has a weird appearance. It is covered with lines mostly -winding and circling about

some central spot. There may be one starting up Winnipeg winding east and south via Detroit to a point in Texas, its central curve roughly paralleling a circle planked down in Omaha or Nebraska. Other lines may skirt down around the Atlantic coast with the central circle somewhere about New York and reaching from Montreal to Charlestown. There are usually a number of these circles scattered over the map with other lines either ringing them concentrically or winding in a vague sort of way from one to the other.

MAKING THE -WEATHER MAP.

To the uninitiated the map looks like a Chinese puzzle, but to the weather man it is all as clear as daylight. The circles and their attendant lines are found to group themselves in two ways Either the pressure increases towards the centre of each circle or it decreases. In the first case the circles are “hio;h areas” and the second “low areas”—“storm centres” in which the winds circle in a direction contrary to the movement of the hands of a watch; in high areas the movement being the other way. Generally speaking, the low areas are, as I say, storm centres, carrying with them unsettled, stormy weather with a tendency towards a warmer temperature. The high areas carry with them fine weather and a tendency to cooler conditions.

In the weather man’s morning map we will suppose that the circle or “area” which he finds centered in Omaha is a low one—that is, the barometric pressures at the various stations get lower and lower as they approach that central point. There is therefore a storm centre over in the middle west; the reports of actual weather conditions indicate how bad the storm may be, whether it is merely an unsettled state of weather or an actual raging storm of one kind or another; the wind reports evidence the intensity of the atmospheric disturbance.

The direction and speed of travel of the area are deduced from the amount of rate of fall of the barometric pressure. That is to say, the area travels

in the direction towards which the barometric depression is most pronounced. In the weather map for Sept. 13th reproduced with this article, the high area centered in British Columbia would travel eastwards across the place on the map where the isobars are closest together and not southwards where they are spread out, indicating that the “slope” of the high area is not so “steep,” so to speak. • The speed is deduced from the rate of fall.

Roughly speaking the weather man makes his forecasts by keeping an eye on the centre of each particular area. It is travelling eastwards, say, at a certain speed. Very well then; the probable weather in its course can be prophesied with fair accuracy. Of course, the further away from the storm centre the place prophesied about may be, the more likelihood of inaccuracy in the forecast. The Omaha area, for instance, may be travelling north-east, in which case it may be expected to pass over Michigan and so on over western Ontario and upwards into Quebec, its influence stretching on either side over, a district proportionate to its extent. But if it is deflected a few degrees at the beginning it may travel far to the south of the expected course and fetch up somewhere in the Maritimes instead of in northern Quebec. Like the railway time tables the courses of areas of atmospheric disturbance are “subject to change without notice” and the public who are disturbed by the change rise as one man and curse poor “Probs.” just as they furiously rage against the innocent train dispatcher who cannot help himself.

This of course is merely the roughest outline of the work. The areas are not fixed, unchangeable sort of things which can be depended on arriving at their destination in the same state that they started out even if they remain of one mind as to the course they are going to pursue. All sorts of things influence them and change or modify their character.

Many of these influences are the fixed physical characteristics of the country which can be taken accurate account of by the weather man. Mountains, for

example, have a great effect on the atmospheric conditions which butt up against them. The Rockies, so to speak, hold back a lot of “weather” and keep it from finding its way into the Dominion at all; and vice versa. The height of land which stretches from Niagara to Collingwood has the effect of depositing much larger quantities of moisture on its western than its eastern slope. The areas travelling eastwards when they reach the Height of Land are forced upward into the cold upper regions where they are chilled and condensed—the moisture they contained falling as rain or snow. After the area has crossed the Height the area descends again appreciably robbed of moisture and, expanding, easily contains the moisture that remains until a meeting with a cool current of air, another trip into the higher regions, or some other cause condenses it again and results in another rain storm.

FORECASTING DIFFICULT IN CANADA.

Canada is such a “mixed” country that it is especially difficult to forecast its weather or to depend even upon its most dependable qualities. There is a general drift of weather across North America from west to east which “Probs.” can reasonably depend upon, though at times the drift zig-zags across country and even occasionally reverses. The alternations of mountain, prairie, forest and big stretches of water cause all kinds of sudden changes which the weather man is not troubled with in a less varied country such as Australia for example. Piere the great level stretches of desert in the interior and the comparative absence of water make it possible to foretell the weather for as long as four days ahead and when a better wireless service is arranged with ships approaching the Australian coast it will be possible to make still longer forecasts. The Canadian weather man is lucky if he can look a day ahead with any certainty as to accuracy.

The areas travel at all sorts of speeds and sometimes even remain stationary for quite long periods especially in the North Atlantic. That means, of course, that the districts influenced by the area

enjoy “a spell of settled weather,” day after day the same until the area takes it into its head to move on. Moreover, it has due effect on other districts outside that immediate area since it holds up areas that are following and compels them to remain stationary also unless they slide off to one side or have sufficient force to push the opposing area on or force it aside.

Such things as this are, of course, very difficult for the weather man to anticipate. And there are things he does not know; the effect of the change in the electrical potential of the atmosphere”, for instance. If he knew exactly how the free electricity in the air was acting it would be a great help to him.

But everything in nature has an explanation and knowledge is widening. Every year, almost, there is some discovery which gives the work of “Probs.” greater possibilities of accuracy. All the time he is watching the weather less with a view to telling what it will be like to-morrow than to finding out exactly why it was like what it was yesterday.

Half the time “Probs.” is a coroner and his “post mortem” work is of the most important. The Canadian meteorological Department has done considerable useful work in this respect. At Agincourt near Toronto they have made use of kites to explore the upper atmosphere—great kites which would soar beyond the possibilities of an airman’s flight carrying instruments which record the conditions they find existing there. Balloons both captive and free have been used for similar purposes, and many valuable scrape of information have been obtained.

The Canadian weather bureau helped to confirm the theory of the “isothermal” layer. Balloons sent up succeeded in establishing the existence of a layer of atmosphere which has a constant temperature and which surrounds the immediate atmosphere of the earth in which our “weather” takes place. And beyond this again was discovered a second layer of a warmer temperature.

Though practically constant in temperature, these isothermal layers rise or fall in height and their mission is to

act as “indicators” to inner atmosphere. But at best these are only scraps to be patiently pieced together and to be added to from time to time till the weather man’s knowledge of his fickle subject is quite complete.

POSSIBILITIES OF THE FUTUBE.

And when that day arrives, what then? Will we ever know so much about the weather that we can control it, or at any rate modify it to be more in accordance with what we want, Even that day may come, though our few poor, crude attempts as it to-day are mostly failures. Attempts to “make rain” with the aid of dynamite or otherwise have in the opinion of our best Canadian weather men all been failures, and the professed “ram makers” one occasionally hears of are generally classed as fakers. The hail destroying experiments of Southern France and Italy have been among the most sue cessful, but are woefully uncertain. In these regions hail is a very powerful enemy of the vineyards and in many places may be seen curious contrivances something like a cross between a gun and a gramaphone which are used for “shooting” approaching hail clouds and dissipating them before they are a real danger. They are “shot” in actual fact, but the projectile is a whirling vortex of air exactly like a smoke ring which, whirling into the cloud, breaks it up. But the success of this scheme has been very limited and uncertain and its proved value is not great. We will not be liable to claim to control the weather until we can prevent the hail or thunder cloud from forming or can drive it where we will to dissipate itself at some waste spot where it can do no harm—what a thought, by the bye! the Sahara desert as the world’s “storm dumping place” to which all the world’s storms are herded, a region of perpetual thunder and lightning, cyclone and tempest. The idea is ridiculous, of course, but imposing.

No; the weather man laughs at the idea of ever being able to control the weather to any appreciable extent but he looks forward hopefully to the day

when we shall know so much about its origin and habits that we will be able to avoid most of the inconveniences under which we suffer to-day.

And very serious inconveniences some of theiti are, as everyone may realise. To you or me a forecast of the weather may mean no more than to influence us as to what clothes we shall wear, or whether we shall light the furnace. But to the farmer, the sailor, to everyone whose business is affected by the elements an accurate forecast is of the greatest possible service. On the coast to the fishermen a forecast of the winds especially is almost a necessity —and to this department our “Probs” in Toronto and his junior partner in Victoria pay a great deal of attention.

It is odd when you come to think of it, that the fishermen of Newfoundland should look all the way to Toronto to .see what favorable winds they are going to have or what perils of fog or storm they may have to brave. It shows in a very striking way what a triumph of modern centralization is our Canadian “Probs.” It shows too how science has superseded superstition. The fisherman relies on the storm cone and the weather forecast where once he listened to “weather wise” old veterans or relied implicitly on “signs” and the movements of animals or fishes. Most of the old popular weather signs are utterly discredited and the weather man can show good long lists of statistics to prove them wrong—the St. Swithin’s Day superstition for example. In some of them there is just that grain of truth which makes a falsehood all the falser but practically none of them is to be relied upon. Statistics show that for every time a superstition happens to be right there are many more times that it is wrong.

Superior to all superstition, sitting in calm isolation, the weather man hovers over the North Pole and casts a comprehensive eye over the whole northern hemisphere. He and the telegraph editor of the newspaper are the men who get the world’s news first—and the weather man ranks the higher of the two, for what news is more important than the weather.