Meteorology; An Introductory Treatise

METEOROLOGY - PREFACE - There are many classes of the coininunity to whom the weather conditions are of the utmost importance. The aviator, the farmer, the sailor, and even the holiday-maker are all interested in the state of the weather, though in very different ways. The study of the weather from one mans point of view is therefore a very different thing to a study of it from anothers point of view. But though the subject may be developed along different lines by different sections of the community, yet the principles underlying it are in all cases the same. The present book has been written with the view of indicating these principles, putting them in their simplest form, and avoiding, as far as possible, the use of rnathematical language. In this way the student who has only an elementary training in mathematics will be able to follow the reasoning. Also, as the book is intended to serve as an elementary textbook, I have endeavoured to avoid developing any one part at the expense of another. Any chapter might quite easily be expanded into a book in itself, but in so doing the object for which the book is written would be lost sight of. Meteorolo yl, i ke many other sciences, is developing very rapidly at the present day, and in a book of this type it is impossible to embody all the latest developments. The discovery of the conditions within the upper atmosphere or stratosphere has influenced the development of modern neteorology to a very great extent. Throughout the book, therefore, the strat, osphere and its influence have been kept before the reader. - PLAN OF THE BOOK - The book may be very conveniently divided into three, main sections, together with the final chapter whereinapplication has v been made of the conclusions arrived at in the preceding chapters. Section - one, consisting of three chapters, forms the introductory part. Herein are found a short historical sketch of the subject, and methods of attacking and solving certain meteorological problems. Likewise the atmosphere, that gaseous envelope in which all meteorological phenomena take place, is dealt with briefly, while a short chapter is devoted to the study of solaIr radiation. The next five chapters constitute section two, and deal with the subject-matter of meteorology itself. In treating of temperature I have employed the gas scale throughout, indicating at the same time the relation between it and the other scales. By this mea, ns all negative values are got rid of. Also all problems involving the alteration of temperature through the expansion or the compression of a gas must be treated on this scale, and therefore the plan of recording all temperatures on the absolute or gas scale gets rid of the necessity of conversion. Further, this scale is the only scale on which there is a definitely fixed temperature, namely, the absolute zero of temperature. Pressure is a force, and therefore should be expressed in units I of force. The dyne, the absolute unit of force in the C. G. S. system, is, however, extremely small, and consequently in meteorology the unit - employed is 1000 dynes or . a millibar . The Standard Atmosphere is 1,000,000 dynes per square centimetre or 1000 millibars, and is called a bar . Until comparatively recently, however, all pressures were expressed in - terms of the length of a, column of mercury. But during the last few years the Daily Weather Reports issued by theMeteorological Office, London, have shown the pressures expressed in millibars. Therefore it is essential that everyone who wishes to make use of these reports should understand what a millibar mb. is...