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Meteorology; or Weather Explained

<h1>METEOROLOGY; OR, WEATHER EXPLAINED.</h1>   BY J. G. M’PHERSON, Ph.D., F.R.S.E., GRADUATE WITH FIRST-CLASS HONOURS, AND FOR NINE YEARS EXTENSION LECTURER ON METEOROLOGY AND MATHEMATICAL EXAMINER IN THE UNIVERSITY OF ST. ANDREWS; AUTHOR OF “TALES OF SCIENCE,” ETC.   LONDON: T. C. & E. C. JACK, 34 HENRIETTA STREET, W.C. AND EDINBURGH. 1905.     <hr style="width: 50%;" /> <div class="border"> The Shilling Scientific Series The following Vols. are now ready or in the Press:— BALLOONS, AIRSHIPS, AND FLYING MACHINES. By Gertrude Bacon. MOTORS AND MOTORING. By Professor Harry Spooner. RADIUM. By Dr. Hampson. TELEGRAPHY WITH AND WITHOUT WIRES. By W. J. White. ELECTRIC LIGHTING. By S. F. Walker, R.N., M.I.E.E. LOCAL GOVERNMENT. By Percy Ashley, M.A. Others in Preparation Printed by Ballantyne, Hanson & Co. At the Ballantyne Press </div>     <hr style="width: 50%;" /> CONTENTS <table border="0" cellpadding="0" cellspacing="5" summary="table"> <tr><td>CHAP.</td><td> </td><td align="right">PAGE</td></tr> <tr><td align="right">I.</td> <td>Introduction</td> <td align="right">9</td></tr> <tr><td align="right">II.</td> <td>The Formation of Dew</td> <td align="right">13</td></tr> <tr><td align="right">III.</td> <td>True and False Dew</td> <td align="right">17</td></tr> <tr><td align="right">IV.</td> <td>Hoar-Frost</td> <td align="right">20</td></tr> <tr><td align="right">V.</td> <td>Fog</td> <td align="right">23</td></tr> <tr><td align="right">VI.</td> <td>The Numbering of the Dust</td> <td align="right">26</td></tr> <tr><td align="right">VII.</td> <td>Dust and Atmospheric Phenomena</td> <td align="right">29</td></tr> <tr><td align="right">VIII.</td> <td>A Fog-Counter</td> <td align="right">31</td></tr> <tr><td align="right">IX.</td> <td>Formation of Clouds</td> <td align="right">34</td></tr> <tr><td align="right">X.</td> <td>Decay of Clouds</td> <td align="right">37</td></tr> <tr><td align="right">XI.</td> <td>It always Rains</td> <td align="right">40</td></tr> <tr><td align="right">XII.</td> <td>Haze</td> <td align="right">43</td></tr> <tr><td align="right">XIII.</td> <td>Hazing Effects of Atmospheric Dust</td> <td align="right">47</td></tr> <tr><td align="right">XIV.</td> <td>Thunder Clears the Air</td> <td align="right">49</td></tr> <tr><td align="right">XV.</td> <td>Disease Germs in the Air</td> <td align="right">53</td></tr> <tr><td align="right">XVI.</td> <td>A Change of Air</td> <td align="right">55</td></tr> <tr><td align="right">XVII.</td> <td>The Old Moon in the New Moon’s Arms</td> <td align="right">58</td></tr> <tr><td align="right">XVIII.</td> <td>An Autumn Afterglow</td> <td align="right">62</td></tr> <tr><td align="right">XIX.</td> <td>A Winter Foreglow</td> <td align="right">65</td></tr> <tr><td align="right">XX.</td> <td>The Rainbow</td> <td align="right">68</td></tr> <tr><td align="right">XXI.</td> <td>The Aurora Borealis</td> <td align="right">71</td></tr> <tr><td align="right">XXII.</td> <td>The Blue Sky</td> <td align="right">74</td></tr> <tr><td align="right">XXIII.</td> <td>A Sanitary Detective</td> <td align="right">78</td></tr> <tr><td align="right">XXIV.</td> <td>Fog and Smoke</td> <td align="right">80</td></tr> <tr><td align="right">XXV.</td> <td>Electrical Deposition of Smoke</td> <td align="right">83</td></tr> <tr><td align="right">XXVI.</td> <td>Radiation from Snow</td> <td align="right">86</td></tr> <tr><td align="right">XXVII.</td> <td>Mountain Giants</td> <td align="right">88</td></tr> <tr><td align="right">XXVIII.</td> <td>The Wind</td> <td align="right">92</td></tr> <tr><td align="right">XXIX.</td> <td>Cyclones and Anti-Cyclones</td> <td align="right">95</td></tr> <tr><td align="right">XXX.</td> <td>Rain Phenomena</td> <td align="right">98</td></tr> <tr><td align="right">XXXI.</td> <td>The Meteorology of Ben Nevis</td> <td align="right">102</td></tr> <tr><td align="right">XXXII.</td> <td>The Weather and Influenza</td> <td align="right">107</td></tr> <tr><td align="right">XXXIII.</td> <td>Climate</td> <td align="right">110</td></tr> <tr><td align="right">XXXIV.</td> <td>The “Challenger” Weather Reports</td> <td align="right">114</td></tr> <tr><td align="right">XXXV.</td> <td>Weather-Forecasting</td> <td align="right">116</td></tr> <tr><td> </td> <td>INDEX</td> <td align="right">124</td></tr></table>     <hr style="width: 50%;" /> PREFATORY NOTE <div class="note"> I am very much indebted to Dr. John Aitken, F.R.S., for his great kindness in carefully revising the proof sheets, and giving me most valuable suggestions. This is a sufficient guarantee that accuracy has not been sacrificed to popular explanation. J. G. M’P. Ruthven Manse, June 10, 1905. </div>     <hr style="width: 50%;" /> METEOROLOGY   <h2>CHAPTER I</h2> INTRODUCTION Though by familiarity made commonplace, the “weather” is one of the most important topics of conversation, and has constant bearings upon the work and prospects of business-men and men of pleasure. The state of the weather is the password when people meet on the country road: we could not do without the humble talisman. “A fine day” comes spontaneously to the lips, whatever be the state of the atmosphere, unless it is peculiarly and strikingly repulsive; then “A bitter day” would take the place of the expression. Yet I have heard “Terrible guid wither” as often as “Terrible bad day” among country people. Scarcely a friendly letter is penned without a reference to the weather, as to what has been, is, or may be. It is a new stimulus to a lagging conversation at any dinner-table. All are so dependent on the weather, especially those getting up in years or of delicate health. I remember, when at Strathpeffer, the great health-resort in the North of Scotland, in 1885, an anxious invalid at “The Pump” asking a weather-beaten, rheumatic old gamekeeper what sort of a day it was to be, considering that it had been wet for some time. The keeper crippled to the barometer outside the doorway, and returned with the matter-of-fact answer: “She’s faurer doon ta tay nur she wass up yestreen.” The barometer had evidently fallen during the night. “And what are we to expect?” sadly inquired the invalid. “It’ll pe aither ferry wat, or mohr rain”—a poor consolation! Most men who are bent on business or pleasure, and all dwellers in the country who have the instruments, make a first call at the barometer in the lobby, or the aneroid in the breakfast-parlour, to “see what she says.” A good rise of the black needle (that is, to the right) above the yellow needle is a source of rejoicing, as it will likely be clear, dry, and hard weather. A slight fall (that is, to the left) causes anxiety as to coming rain, and a big depression forebodes much rain or a violent storm of wind. In either case of “fall,” the shutters come over the eyes of the observer. Next, even before breakfast, a move is made to the self-registering thermometer (set the night before) on a stone, a couple of feet above the grass. A good reading, above the freezing-point in winter and much above it in summer, indicates the absence of killing rimes, that are generally followed by rain. A very low register accounts for the feeling of cold during the night, though the fires were not out; and predicts precarious weather. Ordinarily careful observers—as I, who have been in one place for more than thirty years—can, with the morning indications of these two instruments, come pretty sure of their prognostics of the day’s weather. Of course, the morning newspaper is carefully scanned as to the weather-forecasts from the London Meteorological Office—direction of wind; warm, mild, or cold; rain or fair, and so on—and in general these indications are wonderfully accurate for twenty-four hours; though the “three days’” prognostics seem to stretch a point. We are hardly up to that yet. The lower animals are very sensitive as to the state of approaching extremes of weather. “Thae sea beass,” referring to sea-gulls over the inland leas during ploughing, are ordinary indicators of stormy weather. Wind is sure to follow violent wheelings of crows. “Beware of rain” when the sheep are restive, rubbing themselves on tree stumps. But all are familiar with Jenner’s prognostics of rain. Science has come to the aid of ordinary weather-lore during the last twenty years, by leaps and bounds. Time-honoured notions and revered fictions, around which the hallowed associations of our early training fondly and firmly cling, must now yield to the exact handling of modern science; and with reluctance we have to part with them. Yet there is in all a fascination to account for certain ordinary phenomena. “The man in the street,” as well as the strong reading man, wishes to know the “why” and the “how” of weather-forecasting. They are anxious to have weather-phenomena explained in a plain, interesting, but accurate way. The freshness of the marvellous results has an irresistible charm for the open mind, keen for useful information. The discoveries often seem so simple that one wonders why they were not made before. Until about twenty years ago, Meteorology was comparatively far back as a science; and in one important branch of it, no one has done more to put weather-lore on a scientific basis than Dr. John Aitken, F.R.S., who has very kindly given me his full permission to popularise what I like of his numerous and very valuable scientific papers in the Transactions of the Royal Society of Edinburgh. This I have done my best to carry out in the following pages. “The way of putting it” is my only claim. Many scientific men are decoyed on in the search for truth with a spell unknown to others: the anticipation of the results sometimes amounts to a passion. Many wrong tracks do they take, yet they start afresh, just as the detective has to take several courses before he hits upon the correct scent. When they succeed, they experience a pleasure which is indescribable; to them fame is more than a mere “fancied life in others’ breath.” Dr. Aitken’s continued experiments, often of rare ingenuity and brilliancy, show that no truth is altogether barren; and even that which looks at first sight the very simplest and most trivial may turn out fruitful in precious results. Small things must not be overlooked, for great discoveries are sometimes at a man’s very door. Dr. Aitken has shown us this in many of his discoveries which have revolutionised a branch of meteorology. Prudence, patience, observing power, and perseverance in scientific research will do much to bring about unexpected results, and not more so in any science than in accounting for weather-lore on a rational basis, which it is in the power of all my readers to further. “The old order changeth, giving place to new.” With kaleidoscopic variety Nature’s face changes to the touch of the anxious and reverent observer. And some of these curious weather-views will be disclosed in these pages, so as, in a brief but readable way, to explain the weather, and lay a safe basis for probable forecastings, which will be of great benefit to the man of business as well as the man of pleasure. “Felix, qui potuit rerum cognoscere causas.” —Virgil.     <hr style="width: 50%;" /> <div style="break-after:column;"></div>

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