Physics of the Air Second Edition Book

PHYSICS OF THE AIR PHYSICS OF THE AIR BY W. J. HUMPHREYS. C. E., PH. D. Meteorological Physicist, UnitecTTttates Weather Bureau Author of Weathtr Proverbs and Paradoxes, Rain 1 faking and Other Weather Vagaries, Fogs and Clouds, etc. SECOND EDITION REVISED AND ENLARGED SECOND IMPRESSION McGRAW-HILL BOOK COMPANY, INC. NEW YORK AND LONDON 1929 PREFACE TO THE SECOND EDITION The first edition of this book is out of print. It also is out of date, hence a new edition is in order. An additional Part, Meteorological Acoustics, has been included, and many paragraphs and topffcs have been added. Nothing in the older work has been discarded, though various portions have been rewritten and rearranged. For the con venience of the special student, references are given to important original sources not all, but enough at least to start him in the right direction. It would have been more consistent and elegant, perhaps, if the metric system of units had been used exclusively, but that was impracticable, as it would have required numerous awkward conversions of original data and also unnecessary, since every scientist who, musically speaking, has begun to play tunes and quit just running scales, is quite familiar with both systems. In the course of this revision, many helpful suggestions were accepted from my friend and colleague, Mr. E. W. Woolard, whom I earnestly thank for his unfailing kindness and ever ready cooperation. W. J. HUMPHREYS. WASHINGTON, D. C. December, 1928. PREFACE TO THE FIRST EDITION The physical phenomena of the earths atmosphere are exceedingly numerous and of great importance. Nevertheless, the explanations, even of those well understood, still remain scattered through many books and numerous journals. Perhaps this is because some of the phenomena have never been explained, and others but imperfectly so, but, however that may be, it is obvious that an orderly assemblage of all those facts and theories that together might be called the Physics of the Air would be exceedingly helpful to the student of atmospherics. An attempt to serve this useful purpose, begun in a course of lectures at the San Diego Avia tion School Rockwell Field in 1914, led to the production of the follow ing chapters revised and reprinted from the Journal of The Franklin Institute, 1917, 1918, 1919, - 1 920. The author begs to express his indebtedness to Prof. C. F. Marvin, Chief of the United States Weather Bureau, for numerous helpful criti cisms to Dr. C. F. Brooks, Editor of the Monthly Weather Review, for many excellent suggestions to Prof. 0. F. Talman, Librarian of the United States Weather Bureau, for valuable aid in locating original sources and to Major II. B. Owens, D. S. 0., Secretary of The PVanklin Institute, for his encouraging interest in the vork and invaluable atten tion to the details of its publication. vi CONTENTS PAGE PREFACE TO THE SECOND EDITION v PREFACE TO THE FIRST EDITION vi PART I MECHANICS AND THERMODYNAMICS OF THE ATMOSPHERE CHAPTER I OBSERVATIONS 1 Temperature Pressure Wind Velocity Wind Direction Humidity Absolute, Relative, Specific, Dew Point, Saturation Deficit Humid ity Instrumentation Cloudiness Kinds of Clouds Precipitation Evaporal ion Sunshine Radiation Electrical Condition Optical Phenomena Visibility Sources of Meteorological Information. II. SOME THEORETICAL RELATIONS HETWEEN TEMPERATURE, PRESSURE, AND VOLUME IN THE ATMOSPHERE 26 Dry Air Humid Air Entropy and Potential Temperature The Entropy of Humid Air Temperature Changes of a Rising or Fall ing Isolated Mass of Air Change of Lapse-rate Due to Adiabatic Vertical Convection Lapse-rate in Non-adiabatic Convection Work of Expanding Air. III. OBSERVED VERTICAL TEMPERATURE GRADIENTS 40 Average Vertical Distribution of Temperature during Summer and during Winter Atmospheric Stratification Why the Temperature of the Atmosphere Decreases with Increase of Height. IV...Read More