 Chapter 21 of The Ocean of Air – Meteorology for Beginners This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recorded by David Baer The Ocean of Air – Meteorology for Beginners by Agnes Gibern Chapter 21. More about the Wild Winds In the circulation sketch of the last chapter, showing how the air of the atmosphere flows ceaselessly to and fro over the whole face of the Earth, the two halves of the Earth were coupled together. Not wrongly so, for the bare outline of the general plan is the same to north and south of the equator. Still, one half of the world is very far from being the exact copy of the other half. Exact copies are common enough in human works, but not at all common in divine anti-work. There we have infinite variety, filling up systematic outlines. Since no two leaves of a tree have ever been found absolutely the same in form, it is, to say the least, improbable that one half of the world should be a slavish imitation of the other half. If the entire Earth were covered by one enormous ocean of water, then indeed such a system of winds might be carried out in all of its parts with little or no variation. The circulation of the atmosphere would be in that case less difficult to understand and less interesting to study than it is now. But our world contains much land, as well as much sea, and where land exists, the rapid heating and cooling of it causes great varieties of air currents breaking through general plans to any extent. Broad belts of trade winds have been described in folding the Earth like sashes. These trade winds do exist, and they would exist all around the world throughout the whole year if not hindered, but in places they are very much hindered. Suppose, for instance, a burning desert not far from a trade wind region. The air above the desert becomes in the summer months tremendously heated, swelling in size and flowing upward. Then arises a need for heavier air to flow in from somewhere else towards the desert to restore the lost balance of the atmosphere. The trade wind lies conveniently near, and it is of no use to protest that the said trade is wanted near the equator. Here is the most pressing need for the moment, so the busy trade is bent out of its regular course to become a sea breeze blowing inland, and the needs of the equator have to be supplied from some other quarter. Such needs are always supplied. The balance of the air must be kept. If the steady ordinary winds are not equal to their task, a hurricane or two will intervene, doing in a very short time the work required. Land influences of this kind so often divert the trades that they can only be said to hold full sway over broad reaches of ocean, not usually upon continents. Monsoons in general are merely turned or deflected trades drawn over by overheated land from their proper route. The Indian monsoon is a familiar phrase to most English people, at least to those who have relatives in India. It is commonly applied to the soft southwest monsoon, which brings the heavy rainy season. Footnote. Two monsoons blow regularly in India, taking turns. The southwest monsoon lasts about five months, from May to October. Northeast about another five months, between October and May. Each being divided from the other by an irregular month called the breaking of the monsoon, during which violent storms and even hurricanes often take place in the struggle of the disturbed atmosphere to regain its lost balance. End Footnote. Here is a little description of the rainy season, written by one on the spot, which helps bring it before our imagination. Footnote. Mrs. Murray Mitchell's In India. End Footnote. I wish you could see how it rains. For eleven whole days it has come down incessantly, and the compound is like a lake. People are beginning to grumble, but I like it. The air is so much fresher and pleasanter, and one feels so much more alive than in the terrible heat which preceded this downpour. And then again in August, nearly two months later. The rain is most preserving. It comes down not in ordinary drops, but in sheets of water. The whole place is ankle deep, and I have just been watching the servants wading through the slush with their queer little wooden umbrellas over their heads, bringing in the dishes for breakfast. All Indian kitchens, you know, are at a little distance from the house. Everything is damp and disagreeable and moldy. It is quite an occupation to look after one's books and clothes, and after all no care avails to save them. The books would break your heart. Their faces so fresh and fair when we left home are spotted and spoiled. The very pillows smell as if they've come out of a charnel house. The gloves you wear today are white with mold tomorrow. Your boots the same, and your very hair seems mildewed. Nature, just now, is wildly luxuriant and beautiful. The effect, of course, of the bountiful monsoon. The woods are full of rich loveliness. The varied ditches are turned into beds of beauty, covered thick with beautiful colladium leaves, blotched and streaked with crimson, purple and brown. Now the southwest monsoon is nothing more or less than the northeast trade of that region, completely turned or doubled back upon itself and made to flow in steady currents over India. But what of the northeast monsoon, which flows during the winter months of the north? While that is only our old friend, the northeast trade unchanged. When the influence of the desert lessens through cooler weather, the trade returns to its natural course and flows once more towards the equator. Footnote. The world has other monsoons besides those of India. There are African monsoons, caused by the great African deserts drawing aside part of the Atlantic trade, and there are Central American monsoons, formed out of deflected Pacific trades. And footnote. Perhaps the force of moving air is shown in no more marked way than in its lashing of the ocean surface into mighty waves. Even when standing on the shore, one may gain some idea of the tremendous power of ocean waves, lifted and driven onward entirely by the pressure of the gentle, transparent air, which floats so sleepily around us on a quiet summer's day. Without an ocean of air, the ocean of water would be waveless. As good a view as any of ocean billows, seen from the safe vantage of firm ground, may be obtained on the Chesil Beach, a long reach of shingle extending between Portland and the mainland, some 10 miles in length and rising up to a piled shingle height of about 60 feet. If a strong wind blows from the Atlantic straight up the ridge, a curious contrast can be seen by one standing on the summit. Within, the bay between Weymouth and Portland lies calm and blue, still as a lake, broken only by ripples. Without, beyond Chesil Beach, a boiling sea of great waves heaves wildly, and one monster billow after another, 20 feet or more in height, reaching far along the line of shingle, rolls fiercely up, curls grandly over, and falls with a deafening crash, sending forth a rush of foam and spray, grinding pebbles together and tossing them about like sand. No human being could live beneath the crushing weight of one of those waves. The noise is so deafening, even in a moderate gale, that I have tried in vain to hear words shouted in vigorous, masculine tones, close at my side. In a storm, so mighty as the turmoil, that a small brig has actually been lifted by the sea, carried over the top of the ridge and landed on the shingle slope beyond, when, so a way was made for it later, into the quiet bay. The action of the wind upon the ocean's surface varies much in different places. A greater contrast could hardly be found than between the vast majestic rollers of the Atlantic, a quarter of a mile or more apart, travelling in slow succession, and the broken chopping waves of the channel, dashing into and over one another with impatient and undignified restlessness. Again, one may turn from the stately water-hills of the sea, off the Cape of Good Hope, 40 feet or more from Crown to Hollow, calm in motion and deep blue in hue, to the wild perilous turmoil of the North Sea. One or two quoted descriptions of the latter will speak more forcibly than any words of mine can do, as to the awful power of the wind over the ocean and of the ocean over art that lies in its grasp. The grave fitful waves roll over the doggie, and the steady shrill wind is lulled but seldom. The sea does not run true. Sometimes after a succession of glossy rollers has travelled westward, there comes a furious northerly drift, which is met by a swift whirling currents from the south. The charging waves meet in thunder. The rearmost seas climb in foaming piles over the shattered bulge of those that reel back from the onset, and the wild hurly-burly lasts until the strong set of the westerly roll masters the leaping cross-drift, and then once more the grey sliding procession moves inexorably shoreward. In December 1883, there was another storm that will soon not be forgotten. To say there was a heavy sea expresses nothing. That tremendous convulsion passes the power of descriptive words. A powerful steam carrier was hit by one unlucky sea, which not only burst her, but shivered her into tiny scraps. Strong wire ropes were snapped, like worsted. Wire stays which held tore up great lumps of the bulwarks, and the amazing force of the sea was shown by the fact that the wood of the torn bulwarks was cut as cleanly as if a huge knife had shorn through. Garmoth, lowstoft, and Grimsby harbours looked as if they'd been under heavy shellfire for many days after the gale. Hardly a boat escaped without serious damage, and the wonder is that any of the fleet got home. Footnote, J. Ronselman, and Footnote, and again from the same pan. The wind met one like a solid body, and its savage storming call stunned the nerves. It piled up a sea much worse than several I have seen when a perfect hurricane was blowing. Then the run of the sea was crossed grain, and when two or three charging currents met, they reared up into a hill that fell away like a water spout. Finding that it was impossible to see anything, save a dark flurry of tortured water, or to hear anything, save the numbing thunder of the gale. I tried to snatch some sleep, but it was a hopeless attempt. The vessel was riding beautifully, sometimes when it seemed as if she must actually fall off the side of the sea. She sidled prettily up the flank of the gloomy threatening mountain, topped it like a bird, and swept down the rushing slope without so much as shipping a splash of spray. Harder and harder the wind blew. The rearmost waves strove to climb over the front ranks. The blown spray cut like sharp lashes, and the ugly hills that were veiled by that cruel drift made bellowing sounds as they rushed on their sliding basins. Imagine the brightened downs magnified. Imagine also the surface of the downs covered by tumbling hillocks, and then imagine two or three of the bluffs of the downs terraced one above the other, and you have an image of such proportions of that sea as the eye could take it in at one view. The bright strength and speed of the torn rollers were splendid, but I felt a rage in my heart as I thought that those beautiful, awful waves might kill some of the poor fellows who had been sent out in rickety, ill-found vessels. Such word painting as this makes even a landsman able to faintly realize what it is to be out on the North Sea when the winds are in the rougher moods, but to learn the uttermost strength of the soft air to lift and read the ocean surface into death-dealing waves, we must go to the tropics. On the 31st of October, 1876, more than a million human beings, natives of India, lay quietly down to sleep on certain flat lands about the mouth of the Ganges after it is joined by the Brahmaputra, and on certain low-lying islands at its mouth. The islands are built out of the soil which is constantly carried down by those two great rivers. The people counted themselves safe that night, safe as usual. All particular fears troubled them. They knew that these low, unprotected lands were subject now and then to sudden inundation from storm waves, lashed up by a circular hurricane on the ocean and brought to their shores. But such catastrophes were only occasional. They had taken precautions. They had built their little huts on platforms or mounds of earth some three feet in height, and they had counted themselves fairly secure. At ten o'clock a storm raged, but without any unusual features, one of the ordinary cyclonic storms of the tropics. But at the hour of midnight came an awful warning cry, passed on from man to man and overtaken by the hurring foe. The water is upon us. One cyclone wave after another, drawn up at sea in the whirlwind center, was launched ruthlessly by the fierce scale over the islands and the low-lying mainland. The rushing tide bore all before it. No less than three thousand square miles of country lay soon under water from ten to twenty feet at least in depth. Little use were the hut platforms against this mighty incursion. Thousands of inhabitants died at once, died in their sleep, or woke up to a moment's agony before they perished. Some climbed the trees near their huts. Others were flung by the rough billows into the branches. Some floated on the roofs of their huts, torn away from the mud walls, and others clung to the logs of wood. But too many of these were carried hopelessly out to the sea. The flood did not last long. By morning it was subsiding, and by noon the unhappy refugees in treetops could descend. But wind and wave had done too surely their fearful work. Two hundred and fifteen thousand human beings were destroyed in one half hour by a single fell swoop of the elements. The Great Water Circulation It is hardly possible to gain a clear idea of water circulation generally without a few words first on the subject of ocean circulation. These two fluids, air and water, are intimately bound together, so intimately that neither can be long viewed without some reference to the other. The two oceans, that of air and that of water, are to a very great extent governed by the same laws, far more so than we, living at the bottom of the air ocean, would naturally suppose. Water is water, wherever it may be, always strives to keep its own level to present a perfectly even upper surface. Whether a mass of water be larger small, it can never remain at rest with one part of its surface higher than another part. A stream immediately flows from the upper to the lower surface to restore the lost level. This is much the same as we have seen in the ocean of air. True, we do not talk of a gas or a portion of air keeping its level since a gas can spread out equally well in all directions. But, when we consider the ocean of air as a whole, we find it following almost the identical rules of an ocean of water. The manner in which it flows to and fro to preserve above what may perhaps be called a level surface but all events to arrange that equal quantities and weights of air shall be over all parts of earth's surface has already been explained. Another rule is common to the two oceans. We have seen in the circulation of air how every current of air makes needful a second or counter current. It is the same in the circulation of ocean waters. Every current of water flowing one way makes needful a second current the other way. Just so much water as passes from the north to the south must also pass from the south to the north. Just so much water as pours towards the equator must also pour away from the equator. If not, all ocean waters would gradually collect in a vast heap upon one part of the ocean bed while other parts would be left dry. Many causes combine to keep the ocean in ceaseless unrest. Winds blow over its surface from all quarters of the compass bearing the surface waters with them. Unequal heating of one part and another causing some waters to expand and grow light while others remain cold and heavy is a fruitful source of currents. Fast quantities of water are daily drawn up by the sun into the atmosphere from one place to be poured down in another thus further disturbing oceans balance. Mighty rivers rush from the land each making fresh readjustment needful. The tide sweep to and fro day after day stirring up the great expanse anew such and countless other disturbing forces render a petrified and changeless ocean impossible. He causeth his wind to blow and the waters flow. These are words written very long ago yet true now as them. The power of winds to produce currents in the ocean has been often questioned but there can be no doubt that such persistent winds as the trades have great influence in causing steady and continuous surface drifts. Each of the five chief oceans has its own separate circulation the entire mass of water moving slowly around in an enormous eddy before going on elsewhere. A most weighty part in the Atlantic eddy is played by the Gulf Stream. It seems strange to think of an actual river in the ocean yet many such exist. The Gulf Stream is an actual river of warm water flowing northward out of the tropics upon a bed of cold water with cold water banks. The distinction between the warm Gulf Stream waters and the cold ocean waters is so sharp that a ship may lie across half in the stream, half in the ocean the line of separation being plainly seen. The Gulf Stream waters are not only much warmer but much salter and therefore of a much deeper blue than the ocean waters. If the river gained and lost heat as quickly as land does the Gulf Stream would be of very little use to us in the British Isles but happily it is not so. The thick underlying cushion of cold water keeps the Gulf Stream from the ground which would fast steal its warmth and so it pours onto British shores holding still a good deal of its tropical heat. On first leaving the Gulf of Mexico the stream is about 30 miles wide at a rate of 360 feet each hour. By the time it is wandered as far north as Newfoundland it is over 300 miles in breadth and moves much more slowly yet it is still distinct from the ocean. We may see in the Gulf Stream a remarkable illustration of that enlarging which was spoken of a little earlier in connection with heated air over a desert and over the tropics. The waters of the ocean river being much warmer as the ocean around expand or swell outwards. The central line of the Gulf Stream off Hatteras stands about two feet higher than the ocean level partly indeed from rapid motion between confining banks but partly also from the increased bulk of the heated water. In consequence of this perpetual surface streams pour from the top to either side. Colder and heavier waters find their way in below and the Gulf Stream is gradually forced upward the stream flowing in a bed which steadily widens and grows more shallow. The swelling of the heated water the two outflowing surface streams above and the two inflowing cold currents below seem to be on a smaller scale very much the same that we have seen to take place in the ocean of air over the equator resulting in trades and anti trades. So distinctly does the surface slant downward to either side that floating seaweed and driftwood are known never to find their way across the Gulf Stream. They cannot do so for they would have to climb a hill and ridge of water. All the rivers run into the sea yet the sea is not full unto the place from whence the rivers come thither they return again. That is precisely what happens all the rivers speaking generally run into the sea. With the exception of the Jordan flowing into an inland sea and a few like instances all rivers find their way not only into the sea of any particular country but into the sea the great ocean. Yet the sea is not full the ocean waters are under restraint. They do not rise up to swamp and overpower the lands as probably they might if all the water that exists in earth and air found its way to the ocean and remained there. But from whence the rivers come thither they return again. Where do the rivers come from? In a great measure from hill tops and mountain ranges water collects on high lands falling from the clouds draining from snow fields. It pours downward in streams which joined by other streams grow into torrents and swell into rivers running into the sea. What next? These rivers return how and where? They become part of the ocean first the water particles which form the rivers on land now flow to and fro in ocean currents. For a while perhaps they are far down in oceans depths away from sunlight. Sooner or later they find their way towards the surface by and by while there exposed to the sun's heat they pass upward into the air as invisible vapor. Then the air carries them over the land and the heated ground warms the air making it expand and rise upward like wood plunged in water through heavier air overhead. So rising it grows cold again and can no longer contain all its moisture. The once river particles are next pressed gently out of the air as a little mist and they go to join a cloud near. The cloud is born by air occurrence to and fro till perhaps it reaches the very same mountain from which ran the river which brought these water particles down to the sea. The cold mountain peak cools still farther the air in which the cloud rests then heavy showers of rain fall soaking the earth filling the rills and feeding the rivers which run into the sea. Or the mountain and cloud are both so high up in the air that the cloud is frozen and snow falls instead of rain. It comes to the same thing in the end the snow drains out in a river of ice and the river of ice becomes a river of water. Now we see how true it is that from whence the rivers come thither they return again. Do they come from mountain ranges? Mountains receive far more plentiful supplies of rain and snow than level planes. The rain and snow combine to feed the rivers. The rivers feed the sea. The sea feeds the air. The air feeds the clouds. The clouds empty themselves upon the mountains. Do the rivers come from the clouds? That is equally true. Clouds pour down rain. Rain fills the rivers. The rivers supply the sea. The sea surface dries into the air as vapor. The vapor becomes clouds. So whether we start with mountain rivulets or with clouds the circle is complete and we come always round to our starting point. The whole world, land and ocean and atmosphere has been described as a vast distilling apparatus. The warm south seas serve for its boiler. The sun is its furnace. The colder regions north and south are its condensers. We may talk of the atmosphere as a huge pumping engine for pumping up and showering down water. But the atmosphere does not and cannot act alone. It works in company with land and ocean under the sun's control. Tropical oceans steadily heated by the sun's rays send streams of vapor into the air. These streams of vapor pass upward with the steadily ascending air of the equatorial calm belt. Air as it rises becomes colder. Not merely because the upper regions of the atmosphere are colder but because the lessened weight of air above makes it expand and in this act of expanding or stretching a certain amount of heat is given out. Now the air growing colder becomes virtually damper. Not actually damper because it does not contain more vapor than before but virtually damper because it is more nearly saturated more nearly obliged to part with some of its hidden vapor. The next stage is that it does reach a saturation point and does lose moisture which is poured down as heavy rain. The torrents of rain peculiar to the calm belt of the equator were described earlier. Having parted thus with a goodly amount of vapor the air still mounting reaches that level in the atmosphere where the anti-trades flow to north and south. It used to be supposed that the high level currents from the equator carried away immense supplies of moisture to be poured down as rain over the temperate zones beyond cancer and Capricorn over the south of Europe for example. This view is now held with more reserve. No doubt the anti-trades do contain a certain amount of vapor even after sending down abundant torrents near the equator. Great cold however rapidly condenses moisture into cloud and rain and these tropical currents before starting for the north or south reach very high and very cold regions of the atmosphere. They can hardly therefore be supposed to bear away any enormous amount of tropical vapor. The cold which they encounter in temperate countries even in winter can hardly exceed the intense cold of those lofty air levels above the top most mountain peaks ever climbed by man. Whatever moisture the anti-trades still hold when they come down to earth beyond the tropic of cancer can hardly be distilled into cloud or rain by the cold of southern Europe. It would rather be carried away to the far north there to feed the arctic snow fields and glaciers. In an earlier chapter the atmosphere was spoken of as a big invisible sponge always resting on the ocean and becoming filled with water. Near the equator the sponge gets well saturated then passing upward it has a very severe squeeze from the intense cold of higher regions which sends down rain and torrents. With that violent squeeze one would hardly suppose the sponge to be sensitive to further squeezes from the soft air of south Europe. In all these operations as said earlier the real working power is the sun. The atmosphere without the sun would be as the steam engine without furnace fires a very perfect machine no doubt but powerless to act. Air is simply the machine or engine through which the sun acts. The mass carried out by sun and air is indeed no slight one. To raise daily tons upon tons of water out of the ocean to lift these mighty masses high not in one convulsive heave but calmly gently noiselessly with no sign of effort or strain to bear them to and fro lightly as a leaf is carried by the wind to pour them down again on land and sea not in one death dealing cataract not in showers of separate drops. This is what has to be done what is done day after day by the great sun and the obedient air. But for the sun we should have no drying up of moisture no clouds no rain nay but for the sun we should have no glaciers or snow fields. For glaciers are fed by snow fields snow fields are fed by clouds clouds are fed by invisible vapor in the air vapor is lifted out of the sea into the air by the sun. So without sun heat there could be no floating vapor without vapor no clouds without clouds no snow without snow no glaciers a curious chain of causation distinctly providing that the ice rivers of Switzerland and of the Arctic regions have their origin in the heat of the sun. Indeed the greater the power of the sun in the summer of southern lands the larger are the supplies of vapor drawn into the air. The greater the amount of vapor carried by the winds against mountain ranges or into the north the heavier will be the snowfall. An exceptionally hot summer is often followed by an exceptionally cold winter while a cooler summer means often a warmer winter to come. So round and round in and out the water circulation continues out of the sea into the air out of the air into clouds out of clouds down upon earth from the earth into the ocean or out of snow into water out of water into vapor out of vapor into a snow cloud out of a snow cloud into snow. The course of changes the chain of events may be differently told either way it is a circular chain without a parent beginning or end. End of chapter 22 Chapter 23 of the Ocean of Air Meteorology for Beginners This is the LibriVox recording. All LibriVox recordings are in the public domain. More information or to volunteer please visit LibriVox.org Recording by John Brandon The Ocean of Air Meteorology for Beginners by Agnes G. Byrne Chapter 23 Climate Between the equator and the poles every description of climate is to be found from intense heat to intense cold from utter dryness to utter wetness from perpetual wind to perpetual calm any variety may be had. From Greenland's icy mountain to India's coral strand is a leap which the poet may make an imagination. The traveler can take no such leap in body but must pass through stage after stage leaving from one extreme to the other. It is only at fancy that we see side by side sharply contrasted hot and rainless Egypt with mild and rainy Ireland. Africa's burning plains with the vast Iceland's of Greenland. The awful heat of the Persian Gulf with the awful cold of Siberia. The continuous rains of the tropics with the fitful showers of temperate lands the severe cold and heat of Canada with the moderate seasons of England these and countless opposites all upon one globe come under the head of climate. Climate depends chiefly upon degrees of heat and cold degrees of dryness and moisture degrees of wind and calm in other words it depends upon the state of the air. Human beings taken generally manage to bear pretty severe extremes of heat and cold. Some of the very coldest spots inhabited by Manor to be found in the dominion of Canada and in that awful country of exiles Siberia. A hard working Canadian bishop of the Anglican Communion now living has in the care of his diocese slept for ten days at a time in open air with a temperature of 40 degrees below zero. Pretty severe for a man well on in middle life he might indeed say you in England don't know what it means. We count a winter exceptionally severe. If the mercury stands for any length of time at 20 degrees to 25 degrees above zero but even the bishops experiences are outdone by what unhappy Russian exiles have to endure at certain Siberian stations only his is voluntary endurance there's compulsory. At one of the said stations Wurkojansk the temperature stands habitually through December and January at 56 degrees below zero and often sinks much lower it sometimes descends to 81 degrees below zero. Turning to India for a glance at the opposite end of the scale we find that at Massawa during May the thermometer has been known to stand as an ordinary event at about 99 degrees above zero in the shade occasionally running up to 130 degrees. There's a rough rule for the north or south of the equator means increased cold. There are successive bands of climate around the earth zones of heat followed by zones of mildness then a moderate cold lastly of extreme cold. Each zone has its own peculiar plants and more or less its own range of peculiar animals. Animals have a wider range of plants being better able to adapt themselves to varieties of climate but perhaps man alone can live in almost all climates. It might be expected that the bands of climate around the earth would lie in regular order so much less of heat matching so many miles further to the north but under the modifying influences of air and sea things are very different. Sift lines of latitude drawn on a globe will not at all fit in with lines of climate. The latter are indeed most erratic instead of following the straight and even latitude lines they run further north here and further south there take a sudden bend make an unexpected twist do anything in short except to keep such rules as we should expect but for every bend and twist and loop there is a sufficient cause. Differences of climate depend first and chiefly upon the position of the sun in the sky on whether the sun's rays come straight down from above or slanting from near the horizon within the tropics the sun is always more or less overhead and in polar regions he is never overhead in the summer of temperate lands he is high up in the winter and also in the mornings and evenings of summer days he is low down now in the latter case a sunbeam has to travel a much longer way through the dense damp lower layers of air a great deal of heat is stolen from it by the air on its road there is little to reach earth's surface but when a ray darts downward from overhead it travels through a far smaller amount of damp air so it loses much less of its heat however dazzling this sun may have been overhead on a hot summer's day we are able commonly to look full at him without blinking when he gets near the horizon a far thicker veil of floating moisture cuts off the chief part of his light and heat from our eyes another cause besides the position of the sun in the sky greatly affects climate that is the matter in which the sun's rays are received the great sun acts with most impartial regularity pouring down his beams alike on ground on ocean and on atmosphere but there are two things to be considered in thinking about the power of a sun upon a world one is how the sun bestows his beams the other is how the world is affected by those beams if earth's whole surface were everywhere exactly the same then the sun's rays would take effect everywhere exactly alike since it is made of different kinds of substance partly solid and partly liquid with a varying veil of more or less damp air above this cannot be the case dry ground receives heat quickly and parts with it as quickly water receives heat slowly and parts with it as slowly air receives in parts with heat more or less quickly and slowly according to its degree of dryness or dampness we see the same thing curiously enough in human beings what a man takes in with great ease he has apt to forget with ease in what he gains mentally with toil and effort he does not soon lose water's slow gaining and longkeeping of warmth modifies immensely the climates of earth mighty ocean currents pouring north or south from the tropics carry tropical heat with them to colder parts and make countries which would be frostbound for months rejoice in continuous mildness but seriously as oceans moving waters must and do affect climate their influence will be far less without the help of moving air for after all the waters can do little more in themselves than wash the shores of country their really effective work is to warm the atmosphere above so that currents of air passing from the ocean over the land carry heat with them two or three extracts from travelers reports may help to bring before the mind what is meant by earth's varieties of climate as a variety number one we find in the life of Colonel E. Warburton following account of Australian desert heat experienced by travelers camping in a small oasis the depot was shaded by large trees and by high cliffs notwithstanding which the party suffered terribly from the intense heat the mean of the thermometer for the months of December, January and February was 101 degrees 104 degrees and 101 degrees respectively in the shade under its effects every screw in their boxes had been drawn and the horn handles of their instruments as well as their combs were split into fine laminate the lead dropped out of their pencils owing to the shrinking of the wood the signal rockets, the most valuable item in the equipment of the expedition were entirely spoiled their hair as well as the wool of the sheep ceased to grow and their nails became brittle as glass nor was personal inconvenience all the mystery wrought by this fiery atmosphere port was found to reduce the provisions alarmingly the flower lost more than 8% of its original weight the bran in which their store of bacon was packed became perfectly saturated and weight almost as heavy as the meat they were obliged to bury their wax candles to save them from running into a shapeless mass even a bottle of citric acid became liquid and escaping burnt some linen whilst it was with the utmost difficulty that they could either write or paint so rapidly did the fluid dry in the pans and brushes during the whole of this trying period the leading members of the expedition never ceased in their attempts to find some means of escaping from this oven to east, west, north and south they rode the heated syrup irons blistering their feet and the horses reeking with perspiration though never put beyond a walk again somewhat later we find captain steward returned to the depot and after resting started off afresh discovering Coopers Creek beyond which he encountered his old enemies the sand ridges he mentions the effect of the hot northeast gale the blasts of heat were so terrific that he wondered the grass did not fire this was nothing ideal for everything both animate and inanimate gave way before it the horses stood with their backs to the wind and their noses sunk upon the ground without the muscular strength to raise their heads the birds sat upon the bouts, mute and terrified and the parched leaves fell like snow whilst the thermometer graduated to 127 degrees first its tube going to the expansion of the mercury before fresh supplies reached them the leader had lost the use of his limbs from scurvy his skin became black and the muscles contracted in contrast with the above as a specimen of climate variety number two let us turn to captain scoresby on the arctic regions an arctic winter consists he writes of the accumulation of almost everything among atmospheric phenomena that is disagreeable to the feelings the Greenland sailors being well defended from external cold by a choice selection of warm clothing generally support the lowest temperature after a few days' habitude without much inconvenience when however its attacks are not gradual as when the ship which has attained the edge of the ice under a southerly gale is exposed suddenly to a northerly breeze the change of temperature is so great and rapid that the most hearty cannot conceal their uneasiness under its first impression on one occasion in the year 1814 there was between the time of my leaving the deck at night and arising the following morning an increase in the cold of about 20 degrees this remarkable change was attended with singular effects the circulation of the blood was accelerated a sense of parched dryness was excited in the nose the lips were contracted in all their dimensions and the articulation of many words was rather difficult the hands have exposed would have been frozen in a few minutes a piece of metal when applied to the tongue instantly adhered to it and could not be removed without its retaining a portion of the skin iron became brittle the ship became enveloped in ice the boughs, sides, and lower rigging were loaded again with reference to some seamen who wintered in Zwitsbergen after the commencement of the new year the frost became more intense it raised blisters in their flesh as if it had been burned with fire and if they touched iron at such times it would stick to their fingers like bird lime Mr. Ballantyne's account of winter in Hudson's Bay is to some extent an echo of the above after that, October, until the following April the thermometer seldom rises to the freezing point in the depth of winter it falls from 30 to 40, 45, and even 50 degrees below zero of Fahrenheit this intense cold, however, is not so much felt as one might suppose as during its continuance the air is perfectly calm where the slightest breath of wind to arise when the thermometer stands so low no man could show his face to it for a moment the houses are built of wood with double windows and doors they're heated by means of large iron stoves fed with wood yet so intense is the cold that I have seen the stove in places red hot and a basin of water in the room frozen nearly solid in pleasant contrast with these violent extremes a few words from Miss Gordon Cummings' first impressions of Fiji they serve well for variety number three as regards climate, our impressions are highly favorable we see white men who have been here for years going about without any of the ordinary precautions deemed necessary in tropical climates white umbrellas and solar hats are alike neglected and a white hudgery is considered ample protection in a country where sunstroke and fever are alike rare the thermometer at 90 degrees marks an exceptionally hot day and with the exception of occasional tropical showers we have generally fine weather hot certainly in the midday hours but almost invariably tempered by a balmy breeze and soft grey clouds December is supposed to usher in mid-summer heat and heavy rains not incessant but very much in earnest while they last and for three months we may be liable to hurricanes which however are not an invariable part of the program nor can they possibly be as severe as those of the West Indies or all the frail buildings which compose this little capital would inevitably have long since been leveled with the ground the thermometer has often been spoken of in this chapter a thermometer is a measure of heat and climate is largely a question of more or less heat the little instrument consists of a glass tube ending below in a glass bulb it contains enough mercury to fill the bulb and part of the tube the rest of the tube being partially empty to bear mercury is quickly affected by heat and cold when the surrounding air is very hot the mercury swells in size more rapidly and to a greater extent than the glass so the slender line of it in the tube gently rises when the surrounding air is cold the chilled mercury grows smaller takes less room and sinks lower in the tube End of Chapter 23 Recording by John Brandon Chapter 24 of the Ocean of Air Meteorology for Beginners This is a LibriVox recording A LibriVox recordings are in the public domain For more information or to volunteer please visit LibriVox.org Recording by John Brandon The Ocean of Air Meteorology for Beginners by Agnes G. Byrne Chapter 24 Weather Climate and weather are closely related but not identical For questions of climate we turn mainly to the thermometer For questions of weather we turn mainly to the barometer Yet the state of the barometer has also a very intimate connection with the climate of a place and the state of the thermometer with its weather On the whole weather is a word more used with reference to the temperate zone than the tropical regions When the sun blazes day after day for months out of a blue sky with no change or a sign of change men do not say what beautiful weather but rather what a sunny climate Just as day and summer night and winter merge into one at the poles so climate and weather merge very much into one within the tropics The very rain comes when it does come with a regularity which speaks rather of climate than of weather In our temperate regions our northern belt of variable winds while climate has certain persistent outlines which may be reasonably calculated on weather seems to be a thing of impulses altogether erratic Yet our weather, like all else in nature, is governed by settled laws Weather in England is not more really fitful than in the tropics It is only uncertain in respect of our ignorance The many forces which combine to bring about varying results are more complex than the broader and simpler rules which govern tropical weather and are not so well understood by man Nonetheless, every change of breeze, every passing shower, every cloud which forms and vanishes has had its causes leading up to the present moment One main foundation of climate is the heat of the air in varying degrees A main foundation of weather is the weight or pressure of the air in varying degrees As the warmth of the air is measured by the thermometer so the pressure of the air is measured by the barometer A barometer like a thermometer consists of a glass tube holding a column of mercury, the upper part of glass being as far as possible empty of air Here the resemblance ceases For the mercury column rests in a little vessel open to the air and the atmosphere pressing upon the exposed mercury keeps the slender column upright in the tube just so high as to balance its own heaviness If the pressure of the air weighs exactly the same as the column of mercury 28 inches high then the mercury column will stand exactly 28 inches high in the tube If the air presses harder it will push the mercury column higher If less hard it will let the mercury column sink a little lower A barometer examined first at the sea level and then carried up a mountain will be found on the summit to tell of greatly lightened air But the denser layers have all been left below and the pressure is in consequence much lessened Even at the sea level the pressure is by no means always the same Air there is sometimes lighter through warmth, sometimes heavier through cold Also currents of air especially those which flow upward and downward have a good deal to do with degrees of pressure In the last chapter we heard about certain charts on which are drawn climate curves or curves of equal warmth in different places Charts are made in like manner for the drawing of weather curves or curves of equal air pressure in different places Very often a chart is made which is a union of the two Upon a map of a certain district are drawn the climate lines of a certain date as shown by thermometers and the weather lines of the same date as shown by barometers The map is then filled in with symbols of rain and fine, wind and calm occurring in different parts Thousands of such records have been taken during the last few years Weather curves are even more fitful and curious than climate curves The latter do at least wave and zigzag round the earth keeping in some sort of fashion in one chief direction but the weather curves run fantastically always and form most singular shapes Not any in every kind of shape however Even here we find rules apparently laid down and carried out Even the wild winds have method and order stamped into the very being These weather curves when drawn upon the map fall commonly into one or another of seven distinct shapes or classes known one from another by a practiced eye Some of them such as cyclones and anti-cyclones are familiar to us by name Now nothing is easier than to turn disdainfully away and say, of course Anybody may draw any lines upon a map and make what shapes he pleases But these are not fanciful outlines They follow strictly the actual readings of barometers all over a certain district at a certain time Each barometer reading shows the exact pressure of the air Just when and where it is noted and that degree of pressure always means something definite about the weather Though what it means is not always clear to us Distinctly as the beating of your pulse shows the state of your health the rise or fall of the barometer shows the condition of the atmosphere in respect to its pressure Reading the barometer is feeling the pulse of the air But not everybody with eyes can read a barometer truly Any more than everybody with fingers can feel a pulse, understandingly A man seated in a central office receives news at once from many stations In some of these stations the mercury stands, let us say one particular warning at 29.6 degrees and others at 29.8 degrees in others at 30.0 On this map he draws lines from place to place of the first from place to place of the second from place to place of the third He does not follow any private notions of his own but simply obeys the readings of barometers These lines when drawn form certain shapes and the shapes speak of certain actual realities in the ocean of air One can well imagine that curves so drawn, dictated as one may say by the freaks of the wild winds might fall into any manner of shapes never turning out twice the same yet it is far from being so The wild winds show methods in their madness These shapes do constantly turn out so far alike as to be easily classified Moreover, each kind of shape has a more or less distinct kind of weather belonging to it The air ocean, as we have already seen, is never at rest It is in a condition of perpetual whirl and turmoil Circulating currents stream to and fro Winds pour this way and that way Eddies and ripples innumerable cover the face of the earth A ceaseless conflict of forces goes on Rivers of air to the north are balanced by rivers of air to the south Heat strives with cold and evaporation strives with condensation Heavy air rushes towards light air and light air flees from heavy air In the flow of a great river, there is the general movement of the whole body of water from a higher to a lower level There are also countless lesser flowings to and fro Eddying's round obstructions, silent pools, calm stretches, broken waves and rapids As the river runs, its surface has various risings and depressions Its waters pour many ways, which might be indicated by shapes drawn on paper So too with the atmosphere There are the mighty main streams below and above There are also back streams, side streams, lesser currents, cyclings to and fro Heights and depressions of the outer surface, waves and eddies innumerable One may see baby eddies of air in the road on a windy day Tiny whirls of air carrying round dust and leaves The cyclone is such an eddy on a large scale Varying from fifty to over two thousand miles across And other air disturbances are more or less of the same nature An eddy of water may be either fixed or in motion A river eddy is often long motionless Water particles pour in, circle round and pour out again While the eddy itself is unchanged But some river eddies and most ocean eddies travel onward from one spot to another Forming and vanishing after a fitful fashion There are eddies of air which remain motionless as well as eddies of air which move Anti-cyclones are often stationary for hours and days Even for weeks and months Air particles flow in and out of the stationary anti-cyclone But the great eddy itself gently circling is fixed in one place Some anti-cyclones travel like other eddies Some form, stay for a while where they are, then break up As a rule, air eddies are given to moving on Anti-cyclone like an anti may form anywhere and break up anywhere But it almost always journeys, sometimes traveling straightforward Sometimes creeping round the edge of a fixed anti-cyclone This drifting over us of air eddies is a fact which ought to be clearly grasped Weather comes to us, we do not go to it Men stand still, so to speak, in different kinds of weather sweep past The cyclone comes to give him rain, then anti comes to give him sunshine Each, in turn, drifts onward elsewhere to be replaced by some other form of weather If a man wants a change of climate, he leaves his own climate And goes across land or sea to find something different If he wants a change of weather, he has only, at least in our variable country, to sit still And the change will surely come to him Every face of weather arrives, in turn, as eddy after eddy ripple after ripple Wave after wave journey across the land The weather map which is true of Europe and the Atlantic one morning Has often to be quite altered by the next morning Clearly all the same eddies may be still in existence But the whole has drifted on, so that each spot in the map has changed its weather Where a cyclone was yesterday, a wedge is today Where the wedge was yesterday, a big anti is pushing its way today Where the anti was yesterday, a call has moved today, and so on People are apt to associate the word cyclone with a terrific storm Yet it does not necessarily mean a storm, particularly in temperate regions A falling barometer ushers it in, and it does bring some wind and rain Whether much or little depends upon what is called the intensity of the cyclone It may be languid, or vigorous, or violent But in each case the nature of the eddy is the same The only real distinction between those cyclones Which bring a mild, ordinary amount of wind and rain And those which usher in mighty gales with tremendous rain or snow Lies in the intensity of either The degree of intensity depends upon something else Which is rather difficult to explain clearly in a simple sketch of this kind A little illustration may help Suppose you have to walk up a hill from a level plane The hill may rise slowly or sharply There may be a long or a short space Between the spot where you stand 100 feet above the plane And the spot where you stand 200 feet above it The long space would mean a gradual ascent The short space a sudden ascent In either case the hill is said to rise so many feet in the mile There is a slope also in a cyclone Not the slope of a solid hill, but the slope of different barometer heights Where a cyclone exists the barometer is always lower inside and always higher outside the eddy The rise of the slope from a lower barometer in one place to a higher barometer in another place Is reckoned not by so many feet in the mile But by so many tenths of an inch in the mile To illustrate this suppose you have two barometers daily watching in two towns Three or four miles apart One day the two barometers are the same The mercury standing in both at precisely the same height This means a calm The next day one barometer is two tenths of an inch higher than the other This means a little wind Another day one barometer stands half an inch higher than the other Quite a steep slope This means something of a storm Yet another day one barometer stands an inch and a half or two inches higher than the other A tremendously sharp ascent This means a hurricane Such violent differences within a few miles are seldom and never known in the British Isles But they are by no means unheard of in tropical lands End of Chapter 24 Recording by John Brandon Chapter 25 of the Ocean of Air Meteorology for Beginners This is a LibriVox recording All LibriVox recordings are in the public domain For more information or to volunteer, please visit LibriVox.org Recording by John Brandon The Ocean of Air Meteorology for Beginners By Agnes G. Byrne Chapter 25 Eddies of Air Weather foretellings have been popular in all ages How popular is this fiftiful climate of ours is curious when one sees how often they fail Some signs of rain and fine believed in from time immemorial have foundation in truth Unless fairly often found correct, they would hardly have obtained such a hold upon people's minds Excessive damp on walls springing from excessive moisture in the air is a most natural token of coming rain The red sky and the rainbow of early morning are about equally the shepherd's warning Halos and mocked suns belonging to the van of a cyclone are pretty sure indexes of what may be expected A hollow luminous circle round the moon may not mean rain the next day inevitably But within two or three days it is an almost certainty The old moon in the arms of the new and the clearness of distant hills both the rising from the transparency of the air Are marked signs of rain not far distant About three mornings of white frost are held to be equally infallible Also birds and flowers have a voice in the matter Swallows fly low before rain because insects do the same And many sensitive blossoms close their petals in anticipation of a coming downpour The little red shepherd's glass is famous for its true predictions And a certain pink starry misambry anthem has shown itself almost equal to a barometer in quick understanding of the atmosphere Signs of fine weather popularly held are not fewer in number The opposite characteristics of dry surfaces of a hazy horizon of a crimson sunset of opening flower petals promise fairness The flying far of rocks and seabirds and the flying high of swallows are counted especially hopeful A white moon promises well and so do gossamer webs floating in abundance The difficulty of reading truly all such signs as well as the barometer itself Consists in the fact that the same tokens do not precede all kinds of wet weather Before the rain of an ordinary cyclone the barometer falls but before another kind of air eddy which brings rain the barometer rises Besides these uncertainties one never knows how long an eddy may last At any time a cyclone may die out and vanish A storm may be publicly foretold as traveling to England Signals may be hoisted and precautions taken and after all it may never appear It has either altered its course going off in a new direction or it has quietly broken up and dispersed The foretellings were correct so far as they went but the new freak of the wild air could not be reckoned on Now and then a storm strikes our shores no warning of which has been received This may well happen for cyclones travel fast People often wonder why swift steamers do not come on from mid-ocean in advance of the storm to tell us of its approach The cyclone which should only keep pace with the steamer would be a slow specimen of its kind There is of course the telegraph if a cyclone starts from America instead of taking shape in mid-ocean Notice can be flashed under the ocean and a cyclone cannot compete with electricity This is how we often do here beforehand But even an electric message occupies time Time is consumed in sending it, in receiving it, in transcribing it, in dispatching it to the central office Time there is occupied in examining a great number of telegrams and comparing notes In charting the information received, in sending word to British seaside stations And all this while the big eddy of air is traveling rapidly nearer The very most that can be done generally is to foretell a cyclone, not to say whether it will be mild or severe Various well-known signs belong to the front part of a cyclone such as a watery sun and a pallid moon High hills and mountains show cloudcaps Animals are restless, neurologic and romantic patients suffer more than usual Old soldiers are reminded afresh of their wounds Corns become troublesome and irritable tempers are apt to be upset The weather is dull and oppressive, muggy and cloudy, and more or less warm rain falls when the barometer continues to sink Near the center something of a calm commonly exists surrounded by the revolving winds Patches of rain alternating with patches of blue sky lie within a circle of clouds When about half the cyclone has drifted by and the trough or the line across the lowest depression is passed, a change takes place The barometer begins to rise The sky becomes clearer with wool-packed clouds, the air is more sharp and cold, and the rain if any falls is colder than before A cyclone has been described as an extremely complicated vortex, something analogous to an eddy of water But differing from an eddy of water and that the latter sucks down while the air vortex draws upward It has also been spoken of as a huge irregular funnel of rotating air The winds, whether slight or strong, always revolving round an axis of comparative calm, spirally like a corkscrew inward and upward Whether the vortex of rotating air ever reaches the upper limits of the air ocean or whether it's always confined to lower regions seems uncertain Much obscurity still exists with reference to its nature As the cyclone drifts over a certain place, frequent changes of wind occur It cannot be otherwise, since in no two parts of a cyclone do the winds blow from the same quarter Each cyclone has two distinct motions, not unlike those of Earth The solid body of the Earth revolves upon her axis, so the winds of a cyclone revolve round its axis As the whole Earth journeys through space, so the whole cyclone travels across Earth's surface In our part of the world, cyclones more commonly journey from the southwest to the northeast And then one arrives from the neighborhood of Norway, but by far the greater number come to us from the Atlantic and from America The direction taken by a journeying cyclone is affected by the daily whirl of Earth, much as the direction of trade winds is affected by it A cyclone traveling from the north comes to us from the northeast, while one traveling from the south comes to us from the southwest Air circulation within a cyclone is always according to rule The winds of a northern hemisphere cyclone rotate round the axis in a direction contrary to the hands of a watch While the winds of a southern hemisphere cyclone rotate with the watch hands If you lay a watch upon a map face upwards, you will at once see the way of the winds in a cyclone on any part of the world These rules are reversed in the case of an anti-cyclone Here again we have an eddy or vortex of winds rotating round an axis, though the rotation is sometimes so languid as to be imperceptible But the direction of the winds is exactly the other way from that of cyclone winds Being with the watch hands in the northern hemisphere and contrary to the watch hands in the southern hemisphere Moreover the spiral movement or the suck of an anti-cyclone is downward like a water eddy instead of upward like a cyclone This results in a piling up of the air which helps to cause a high barometer, one of the signs of an anti-cyclone Anti-cyclones mean generally fine weather, cold in winter hot in summer with hazy distances and little wind and commonly with sunshine On the continent a warm anti-cyclone with a cloudy sky is sometimes seen The leading feature of an anti-cyclone is calm with what is called radiation weather There is little cloud or floating moisture to check the quick pouring out of heat from the ground after sundown So in an anti-cyclone we have dew or whore frost In large towns this particular eddy often brings dense fogs Persistent anti-cyclones are found both in the far north and in the tropics as on the icy plains of Siberia and on the burning deserts of Africa Often continuing for months unchanged Probably an explanation is to be found for the main distinction between the two eddies As bringers of rain and bringers of fair weather in their opposite modes of air currents When air rises from below to above as over the equator it commonly has a squeeze from the cold above and sends down rain When air sinks from higher to lower levels it can not only hold all the moisture it held above but it can take in more So the rising air of a cyclone would naturally cause wet weather and the sinking air of an anti-cyclone would suck up floating mists Clear the sky and as a general rule cause sunshine There are rains which cannot be foretold by weather curves on a map The rains for instance of the Indian monsoon of sea squalls of thunderstorms of tornadoes and whirlwinds Simple squalls come at sea and sharp gusts more or less violent lasting generally only a few minutes Two or three such squalls may be seen at once careening over the ocean ruffling its surface About the most simple kind of thunderstorm known is such a squall accompanied by lightning and a clap or two of thunder These squalls are merely little local efforts to restore the balance of the atmosphere Thunder squalls are more common in winter than summer while heavy thunderstorms are more common in summer than winter The cyclones which visit the British Isles are tame compared with what other countries endure Still from time to time we have a sufficiently sharp experience to learn something about the power of a mighty wind Perhaps one of the most fearful ever known to visit our shores was the great storm of November 1703 One year after Queen Anne came to the throne France, Germany and other countries suffered from it And over a great part of England the damage done was excessive In Kent alone 800 private homes were wrecked and 17,000 trees were blown down Scores of churches had their leaden roofs torn off Sheep and cattle and countless numbers died and many human lives were lost The bishop of Bath and Wells and his wife were both killed in bed by the falling chimneys of the Episcopal Palace Eli Cathedral suffered cruelly Of Brighton, Defoe wrote, Bright Helmstone was most miserably torn in pieces It made the very picture of desolation and looked as if it had been sacked by an enemy In the Thames no less than 500 worries sank and the whole mass of vessels, four only of which escaped Were torn from their moorings by the violence of the wind Twelve men of war large and small founded in different places And the wrecked remains of countless merchantmen strewn our coasts The first Eddystone lighthouse was carried completely away leaving a bare reef And of the men within it including the overconfident architect not a trace could be afterwards found Such scenes as these are happily rare in England and the winds even in their more furious moods Have often fought on our behalf against foreign foes No true Englishman can fail to be thankful for the Myhegales of 1558 Which scattered the invincible Armada The Spanish galleons to the far north and drove a terrible peril from our shores Of 150 vessels which left Spain in disdainful pride promising triumph to themselves Only 56 broken ships crept back into port Of Flavid Deus at Disipantur The force of rushing air was direfully shown a few years ago in the Taybridge disaster A terrific gale was blowing when the Edinburgh train quitting the fife side Passed on the long narrow railway bridge which led across to Dundee From 150 to 200 passengers were in the train Story night though it was no one thought of real danger A few minutes quick passage and they would reach the other side The great brick piers and iron girders were counted strong enough to stand any ordinary strain But men had as often miscalculated and no doubt the strain was more than ordinary The train passed onward upon its slender pathway and the passengers within could look down on either side Straight into the wind-toss mullet water word was flashed along the wires to the Dundee station But the train was on its way thither Those at Dundee waited and watched expectantly mindful of the furious storm In the mullet darkness of a December evening they could see the train passing swiftly along the rails Then suddenly a crash of sound could be heard above the howling of the gale And a bright flash of fire was seen near the bridge's center After that a pause The telegraph wires refused to act and the train could not be seen Its arrival was awaited in vain Madly as the wind hurled itself against Aught in its path Two men made their way along the exposed bridge only to find a mighty gap in the structure So far as they could see two or three of the biggest spans were swept away And with them was gone the whole train carrying down its entire freight of human beings Not one survived that awful plunge to tell the tale End of Chapter 25 Recording by John Brandon Chapter 26 of The Ocean of Air Meteorology for Beginners This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org The Ocean of Air Meteorology for Beginners by Agnes Giburn Chapter 26 Whirlwinds and Tornadoes After all, the heaviest storms ever seen in England are but a child's play Compared with the terrific outbursts of tropical lands The whirlwinds and tornadoes, the hurricanes, typhoons and pamperos Of countries near the equator A tropical hurricane or cyclone is much smaller in diameter And travels much more slowly than the cyclone of temperate regions But the whirl of its eddying winds is far more violent A cyclone in Europe will journey at various rates of speed from 20 to 70 miles an hour While a tropical whirlwind seldom moves faster than 10 miles an hour It is, however, infinitely more destructive on account of its greater force of wind The two movements of a cyclone may be illustrated by the two movements of a top As a top spins upon its point, it also travels forward It may spin fast or slowly, and it may travel forward fast or slowly Each movement is independent of the other Or again, a man may walk forward, and as he walks, he may whirl around his head a stone tied to a string If the whirlwind stone strikes against anything or anybody, it may do some damage The amount of damage depends mainly upon the force and rapidity with which the stone is whirled Not upon the speed or slowness of the man's walk So the amount of damage done by wind is in proportion to its violence The harder it blows, the heavier are the objects which it can lift and carry along Footnote An ordinary light or moderate breeze travels from about 12 to 24 miles an hour A strong breeze about 30 miles an hour A moderate gale about 40 miles an hour A strong gale about 50 miles an hour A storm about 70 miles an hour A hurricane about 90 miles an hour How much harder a hurricane can blow, it is not possible to say When winds reach this degree of fury, neither men nor instruments are in a state of for scientific observation End of footnote We're now thinking about the actual motion of air particles When we talk of a wind blowing at such a rate, we mean that the actual substantial particles of air move thus When we talk of a cyclone or whirlwind traveling over the Earth's surface at such a rate We mean that the whole great air wave or atmospheric eddy travels thus While in the eddy, particles of air are circling round the central comb at the speed before mentioned The crowded particles of air flow in and out of each eddy Just as particles of moisture flow in and out of a cloud Just as particles of water flow in and out of a wave While eddy, cloud and wave has each its individual shape and its motion as a whole When a wind blows at a rate of 80 or 90 miles an hour, the pressure of air is tremendous and great damage is done Happily, wind, even at its worst, comes more or less in gusts and bears with varying weight here and there A house may be laid low with a single blast, yet the windows of another house close by may be unbroken Such curious freaks in the action of winds are often seen If it were not so, whole woods and forests would be levelled instead of occasional trees And all the chimneys in the town would come down, for now only a few stacks are demolished Tropical cyclones have usually a patch of blue sky exactly over the center called the Eye of the Storm The circular storms of the tropics are known as hurricanes in the East and West Indies As tornadoes and whirlwinds in the United States as typhoons in China The Pamperos of South America belong strictly to the same class, though the term is often used loosely Whirlwinds vary in size from the tiny eddies of air seen in a street on a gusty day To the terrific tornadoes of the States, which bear down everything before them And the fearful hurricanes of both East and West Indies, which leave desolation in their track As a rule, whirlwinds, whether large or small, probably arise from the meeting of two opposite or nearly opposite currents of air The struggle for adjustment, causing naturally energy The whole history and nature of tropical whirlwinds are still full of difficulty Though marked points of resemblance exist between the hurricane of the tropics and the more gentle cyclone of temperate regions The two are so unlike in many main particulars that it seems doubtful whether they may be close together Near the coast of India, hurricanes are most frequent in October and May, when months soon changes come about The air has many a fierce struggle then to regain its lost balance In these storms, as in the storms of quieter lands, there are barometer disturbances and to a much greater extent The slope of the barometer heights is far sharper At the center of a hurricane, the barometer has been noted as standing fully two inches lower than outside the storm This tremendous difference is but a short distance, for tropical storms are of small extent Must mean a mighty atmospheric, upset, only to be put right by hurricane lasts The word cyclone, footnote, from Greek, a circle And footnote, dates from the year 1848 Until nearly the middle of the present century, the circular shape of hurricanes was not even suspected Many a good shape has been lost for want of this knowledge Caught in a sudden hurricane, it would battle onward unconsciously towards the center There it would meet with either comparative stillness in the way of wind Or with violent and changeable gusts, and in either case with a rough chopping sea Still, the worst of the storm would seem to be over, and the sailors would be rejoicing in their escape Perhaps spreading sail more freely, when a fierce roar of renewed tempest would burst forth from just the opposite quarter to that which they had before encountered Too often, ship and sailors were lost in the fresh peril It will readily be understood, have a vessel crossing a circle of wind Must necessarily meet opposite winds on the two sides of the circle Now that the laws of cyclones are better understood, a captain finding his vessel overtaken by one Knows in which direction to steer, so as to avoid getting near the center, and to escape as fast as possible One of the most fearful of modern cyclones was that of October 7080, which started from Barbados and travelled to Bermuda English ships of St. Louis were destroyed, and 40 French transports of Martinique, carrying 4000 soldiers, were lost, simply vanishing with all on board In Martinique, 9000 people died, and in St. Pierre, not a house remained standing At Port Royale, 7 churches and 1400 houses, as well as the cathedral and the hospital, were all reduced ruins, and 1600 sufferers perished in the latter At St. Lucie, men and animals were lifted up and carried by the wind, and a heavy gun was swept 30 yards from where it stood 14 houses of the 600 dwellings in St. Vincent alone remained when mourning dawned, and not a leaf of twig clung to the stripped trees in the neighborhood Footnote from the atmosphere End of footnote A Chinese typhoon is much the same as an East or West Indian hurricane, equally violent and destructive One which passed through Canton in August 1862, left between 8 and 9000 dead A gentleman living there wrote afterwards, footnote, leisure hour 1862, end of footnote The gale commenced in Canton to blow with fury at about 11 o'clock The river was a fearful sight, a usually placid stream, no wider than the Thames It suddenly converted into a stormy sea, the waves lashing, the shores with angry fury Their dreadful aspect increased by the dull, leaden hue cast of the clouds and water, and even on the very atmosphere Air and water seemed completely intermingled and undefined Howling and roaring, they fly past with impetuous speed, carrying with them thousands of boats Many of them bottom upwards are broken to atoms by constant collisions And human beings beyond the reach of help Nor are disasters confined to the river Onshore, houses are constantly falling and walls stumbling with a crash Hundreds of families are in a moment, rendered houseless The sky is now clearing, the storm has lasted not quite two hours It has been blowing from northeast The sun begins to peep out, the wind subsides as rapidly as it rose Not a leaf stirs, there is a death-like stillness But what is that, hark, I, and before the question is answered, more furious than ever blows the blast from the opposite quarter of the compass Wrackers of lot and looters ashore are taken by surprise And many pay for their temerity in their dishonest calling with their lives The same scenes again occur, and after an hour or two the wind again But more gradually subsides, and eventually gives place to fine weather A clearer illustration than this could hardly be given Of the manner in which the whirling eddy of air passes over a place, bringing in succession most contrary winds The chief characteristic of the American tornado seems to be its extraordinary funnel of dark cloud Formed and helped by the revolving winds Masses of dust swept up from the earth are mingled with masses of moisture Making what looks like an upright spout of cloud or mud Where the tornado passes over a lake or the sea, this becomes a veritable waterspout The spout may be only a few yards in diameter, at its thinnest Videding below and above as it reaches down to earth and up to the level of low-lying clouds The whole area of the storm is often not more than a few hundred yards across The entire whirlwind travels at a rate of about 30 miles an hour, or as fast as a moderate train Within that limited space all is destruction, the great eddy leaving utter ruin in its track Solid buildings are levelled with a single blow, or lifted and turned around before being torn to pieces Such a tornado took place in May 1879, ushered in as usual by close heavy weather Rain began to fall, changing rapidly to furious hail Some of the stones were found afterwards to be three and a half inches in diameter And one at least weighed a quarter of a pound The dark, inky, funnel-shaped cloud formed gradually A revolving mass of moisture, dust and mud, upheld by the weight of the revolving hurricane Its roar could be heard three or four miles off Whatever lay in its path was seized world round and round and carried onward The whole diameter of this storm was only about 43 yards And the height of the funnel was supposed to be about 500 feet As an instance of the ruin wrought, a huge blob weighing 700 pounds Was caught up and borne bodily over a space of 20 yards A woman was carried like a feather for 200 yards Then dashed against a wire fence, not only killed but stripped of all her clothing And deluged with black mud from head to foot When the storm had gone by, there came over its desolated track A rush of burning air and then an ice-cold gale from the northwest Footnote from Abercrombie's weather and footnote We may be thankful that such visitors do not come to England Wildly as the winds often howl around our shores We have, after all to do, chiefly with the milder moods of the air-ocean Our countrymen in other lands, our ships in far away ports Come in, as we have already seen, for these fearful outbursts of atmospheric fury And a notable instance took place lately in the Samoan Hurricane Footnote, early in 1889, end footnote Some German and American vessels and His Majesty's ship Caleop Were at anchor in the Bay of Apia, when a tremendous cyclone burst suddenly upon them The waters of the bay were lashed into a fury of waves Among which the ships were tossed about one against another Or flung upon beach and reef, helpless to resist Some were wrecked, some foundered, and there seemed no way of escape from the desperate peril Two German vessels and one American's loop were lost When the captain of the good ship Caleop came to a brave resolve She had already been flung against the Vandalia, and a collision with the Trenton was near Anchors and engines together were failing to save the American and German ships But Captain Cain knew the power of his engines, the spirit of his men He determined to slip his cables, to trust to the engines alone And to throw the head of his ship into the very teeth of the hurricane This done, there was a brief pause, the powerful engines at work The Caleop remaining absolutely at rest, as the winds howled madly past It must have been a pause, however brief, of unutterable suspense For upon its outcome hung the fate of the ship, and probably the life or death of the crew Then, slowly, slowly, the corvette stirred, moved onward, and crept by inches at a snail's space Out of the fatal bay, away to the safety of the open sea As she passed the Trenton, a ringing cheer rang out from the brave Americans Able in their own deadly peril to appreciate the courageous daring of the English captain One is glad to know that though the Trenton was lost, her crew escaped The hearty cheer was heartily returned, and the Caleop was saved But the powerful engines, ordinarily capable of carrying her through the water at a rate of 15 knots an hour Were able to make only about one knot an hour against the fury of the blast End of Chapter 26 Chapter 27 of the Ocean of Air meteorology for beginners This is a LibriVox recording. All LibriVox recordings are in the public domain For more information or to volunteer, please visit LibriVox.org Recording by Elizabeth Miles The Ocean of Air meteorology for beginners by Agnes Gebern Thunder and Lightning Chapter 27 Thunder and Lightning One of the most wonderful and awe-compelling sights to be seen in our Ocean of Air Is a brilliant flash of lightning with its attendant roar of sound Severe cyclones, whether temperate or tropical, besides bringing fierce winds, heavy rain and furious ocean waves Are usually accompanied by lightning and thunder The thunder and lightning of the tropics are such as we never hear or see in our island home Yet even in England death from a lightning flash is no unheard of event Indeed, taking them all around the cyclonic thunderstorms of temperate climates and of cold seasons Are really more dangerous than the heat thunderstorms of the tropics and of very hot summers Though the lightning may seem less severe, the clouds lie lower down And the passage of an electric spark, not merely from cloud to cloud, but from a cloud to the earth, is more common Two kinds of lightning are commonly known to us, zigzag or forked lightning and sheet or summer lightning The second of these is in most cases only a reflection of the first When we look at the flash itself, we call it zigzag or forked lightning When we look at the reflection of that flash on the clouds and in the air, we call it sheet lightning Summer lightning is often the faint reflection from a storm, either too far off, too low down beyond the horizon Or too high up above intervening clouds for us to see the forked flashes themselves Occasional instances of summer lightning cannot, however, be thus explained There is a curious vagueness in the minds of people generally as to the duration of a lightning flash A statement was lately made in the leading tale of a well-known serial that a certain flash lasted fully half a minute A flash really lasts no more than the nearest fraction of a second, some say the ten-thousandth, some say the millionth of a second None know exactly No doubt it seems to continue longer since the retina of the eye keeps for a brief space any impression which falls upon it This may be shown with the help of a spinning top If a piece of paper full of large holes is made to whirl with the top, it will appear to the eye like a continuous sheet of paper The holes in the paper are, so to speak, filled up by the picture of the paper between the holes remaining on the retina as the holes rush by So though the actual flash of lightning is over with almost unimaginable rapidity, its radiance lingers on the retina of the eye for a much larger part of a second But a half a minute? Never The most rapidly moving or whirling bodies ever seen on earth always appear perfectly still when seen by the light of a lightning flash This is a sure proof of its extreme speed A good many thunderstorms have already been described in past ages under other names Hailstorms, cyclones, tornadoes, hurricanes, severe gales, even violent snowstorms are more or less accompanied by thunder and lightning From time to time individuals are struck and either injured or killed, but such accidents are comparatively rare Some years ago a gentleman and lady were staying in Wales, not far from Cardigan, when a heavy storm took place at night The lightning struck the house and the very bed on which they lay was burned, yet they escaped with their lives At another time Derbyshire was visited by a severe storm, the lightning struck a certain grange passing downwards into a room where tea was going on The master of the house was killed on the spot while his wife and a servant were both hurt But such instances as these have to be selected from among thousands of cases where no material damage is done We come now to the question, what is a lightning flash? It is the visible passing of electricity from one cloud to another, from a cloud to the earth, or from the earth to a cloud And what is electricity? For a long while it was believed to be an extremely thin fluid creeping into and flowing through other substances Some held that it was a single fluid, acting in two modes, some that it consisted of two different fluids The idea of electricity being a fluid is now laid aside It is believed to be not a fluid, but one of nature's forces, or forms of energy, acting in the case of thunder in and through the atmosphere We continue, however, to speak of the electric fluid The term is a convenient one and it has grown into general use, so as not to be easily given up Globular lightning, so-called, is still much of a mystery There can be no doubt about the actual phenomenon, but people are apt when it appears to be too much startled or agitated for calm observation It takes, usually, the shape of a bright ball of fire traveling deliberately through the air and exploding with a crash In size it is said to vary from a few inches to two or even three feet in diameter One such ball was seen in Paris descending from the sky, and when it burst, forked flashes seemed to dart from it Forked flashes might, however, easily come from friction, like the excitement of electricity in the aurora Another was seen in England, rising from the ground and zigzagging upwards till it passed into a dark cloud A third was seen in Ireland, floating leisurely over the ground, now and then dipping into the boggy soil Where each time it dug a deep hole or trench, and at length burying itself in the earth It seems probable that a fireball partakes rather of the nature of a meteorite than of a lightning flash If so, it does not come under the head of electricity The phenomenon altogether is a matter for doubt End of Chapter 27