Meteorology: the Science of the Atmosphere

Volume One

P. F. COLLIER & SON COMPANY NEW YORK

Copyright 1922 BY P. F. COLLIER & SON COMPANY

MANUFACTURED IN U. S. A.

METEOROLOGY THE SCIENCE OF THE ATMOSPHERE

BY CHARLES FITZHUGH TALMAN

CHAIRMAN, COMMITTEE OF PUBLIC INFORMATION, AMERICAN METEOROLOGICAL SOCIETY

P. F. COLLIER & SON COMPANY NEW YORK

PREFACE

Meteorology is the science of the atmosphere and its phenomena, including weather.

Nowadays, when we speak of a “meteor,” we generally mean a shooting star; but formerly this term was applied (and it still often is in technical literature) to a great variety of phenomena and appearances in the atmosphere, including clouds, rain, snow, rainbows, and so forth. That is how the science of the atmosphere came to have its present name.

Meteorology is not a branch of astronomy. These two sciences are as different from each other as zoölogy is from botany. They are both founded on physics, and they “overlap” each other to some extent, just as every science does certain others; but if you want information about the atmosphere, weather and climate, an astronomical observatory is not the place to seek it; while if you wish to make inquiries about comets, sun spots, eclipses, standard time, or the date on which Easter fell in the year 1666, do not apply to the Weather Bureau.

In the city of Washington the Government maintains an astronomical and timekeeping institution known as the Naval Observatory, and it maintains in the same city the central office of the United States Weather Bureau. The two establishments are a mile apart in space and nearly a whole library apart in the subjects with which they are concerned. The fact that their functions are persistently confounded by the public indicates the necessity of writing this preface to a popular book on meteorology.

CONTENTS

CHAPTER PAGE I. THE ANATOMY OF THE ATMOSPHERE 9 II. THE RESOURCES OF THE ATMOSPHERE 24 III. THE ATMOSPHERE AS A HIGHWAY 39 IV. DUST AND SMOKE IN THE ATMOSPHERE 52 V. WEATHER AND WEATHER INSTRUMENTS 66 VI. CLOUDLAND 90 VII. PRECIPITATION 106 VIII. WINDS AND STORMS 123 IX. ATMOSPHERIC ELECTRICITY 141 X. ATMOSPHERIC OPTICS 164 XI. ATMOSPHERIC ACOUSTICS 186 XII. CLIMATE AND CLIMATES 197 XIII. ORGANIZED METEOROLOGY 212 XIV. WEATHER MAPS AND FORECASTS 224 XV. AGRICULTURAL METEOROLOGY 245 XVI. COMMERCIAL METEOROLOGY 261 XVII. MARINE METEOROLOGY 271 XVIII. AERONAUTICAL METEOROLOGY 284 XIX. MILITARY METEOROLOGY 306 XX. MEDICAL AND PHYSIOLOGICAL METEOROLOGY 316 XXI. WEATHER-MAKING 332 XXII. ATMOSPHERIC BYWAYS 346 GLOSSARY 365

LIST OF ILLUSTRATIONS

FUNNEL-SHAPED CLOUD OF A TORNADO Frontispiece Painted from an unusual Photograph

FACING PAGE

EXPLORING THE UPPER AIR--BEGINNING OF A PILOT BALLOON FLIGHT 32

EXPLORING THE UPPER AIR--SENDING UP A SOUNDING BALLOON 32

METEOROGRAPH FOR USE WITH A SOUNDING BALLOON 33

KITE METEOROGRAPH TO BE SENT ALOFT ATTACHED TO A KITE 33

ALTO-CUMULUS--FLEECY MASSES SHOWING BLUE SKY BETWEEN 96

CUMULUS, OR WOOL-PACK CLOUD 96

MAMMATO-CUMULUS, OR “RAIN BALLS” 97

CUMULO-NIMBUS--THE THUNDERCLOUD 97

CLOUD BANNER OVER MOUNT ASSINIBOINE, CANADIAN ROCKIES 100

CIRRUS, WITH LOWER CLOUDS IN THE FOREGROUND 100

LENTICULAR CLOUD OVER MOUNT RAINIER 101

ICE STORM AT PHILADELPHIA--TREES COVERED WITH GLAZE 116

NIEVE PENITENTE IN THE ARGENTINE ANDES 117

CLOUDS OR FOG CASCADING THROUGH LAST FORK CAÑON INTO SANTA ANITA CAÑON 136

CLOUDBURST IN SOUTHERN UTAH 137

PHOTOGRAPHIC ANALYSIS OF LIGHTNING--SINGLE AND DOUBLE DISCHARGES 160

PHOTOGRAPH OF LIGHTNING, SHOWING “BLACK” FLASHES 161

ATMOSPHERIC ELECTRICITY INSTRUMENTS 161

GLASS WEATHER MAP IN THE UNITED STATES WEATHER BUREAU 224

THE SUN DRAWING WATER 225

ORCHARD HEATERS IN OPERATION AS PROTECTION AGAINST EXPECTED FROST 256

SNOW SURVEYOR AT WORK, USING A CYLINDRICAL SNOW SAMPLER 257

SNOW ROLLERS, OR WIND-BLOWN SNOWBALLS 257

BED OF THE POTOMAC RIVER PHOTOGRAPHED FROM THE AIR 288

DRILLING WITH COMPRESSED AIR IN A COPPER MINE 289

LAUNCHING A WEATHER BUREAU KITE TO EXPLORE THE AIR OVER THE OCEAN 289

WEATHER BUREAU KIOSK, UNION SQUARE, SAN FRANCISCO 320

UNITED STATES WEATHER BUREAU STATION AT PEORIA, ILLINOIS 320

CENTRAL OFFICE OF THE UNITED STATES WEATHER BUREAU AT WASHINGTON 321

CHAPTER I. The Anatomy of the Atmosphere

THE ANATOMY OF THE ATMOSPHERE

Two quite different conceptions of the substance called “air” are current in the world. One has prevailed from time immemorial. The other is wholly modern. One is the popular view, the other the scientific.

Ancient philosophers regarded air as one of the four “elements” of which all things were supposed to be made. Average humanity, though it did not concern itself with philosophy, must have begun, almost as soon as it realized the existence of air at all, to think of it as something that, however it changed its state from hot to cold, dry to moist, pure to impure, was fundamentally uniform--a single entity. Certainly this idea is in full vigor today. The air that we breathe, supply to our fires, stir with fans, pump into bicycle tires, fly in--the air that asserts its independence of our will in the wind and the weather--gives us the impression of individuality. We instinctively rank it with water among the simple, definite things in the repertory of nature.

Even the man of science often finds it convenient to discuss and deal with air as if it were a single substance, but he is well aware that it is nothing of the kind. He knows that it is, in fact, a jumble of gases having very different properties. Some are heavy, others light. Some are chemically very active, others extremely inactive. Some are abundant, others very rare. These gases constitute the earth’s atmosphere. Other planets have atmospheres that are quite different in composition from ours. The sun itself has a very complex atmosphere.

The earth’s atmosphere is, then, a collection of gases, which are mixed but not chemically combined. Some of them are themselves chemical compounds. Each of these gases behaves very much the same as if the others were not present, and each of them has its separate business to perform in the economy of nature. For example, a tree draws upon the store of carbon dioxide gas in the atmosphere to build up its tissues. Presently the tree is cut down and its wood is burned for fuel. In this process a different atmospheric gas is brought into play. We often say that the “air” supports combustion--that we supply “air” with a bellows to make a fire burn more brightly--but it is not the air as a whole that enables things to burn. Four-fifths of the atmospheric substance takes no part in the process. We burn with oxygen alone. So it is with breathing. Oxygen and not air constitutes the breath of life.

Near the surface of the earth the proportions of the more abundant gases mixed together in the air are remarkably constant. Ignoring a variable admixture of water vapor, oxygen is always about 21 per cent, by volume, and nitrogen about 78 per cent. The remaining 1 per cent is mainly argon. At great altitudes, however, these percentages no longer obtain. The atmospheric gases differ greatly among themselves in weight, and in the high atmosphere, where they are not mixed by the winds, as they are below, the heavier tend to settle to the bottom and the lighter to float on top, as oil floats on water. It is calculated that at a height of thirty miles above sea level the percentage of nitrogen is about 86½ and of oxygen only 10, while at the same altitude the gas hydrogen, which at low levels constitutes less than one-hundredth of 1 per cent of the atmosphere amounts to more than 2½ per cent. Going higher, the percentage of hydrogen is supposed to increase rapidly, until, at an altitude of forty-eight miles, the atmosphere is more than half hydrogen, and at eighty miles above the earth this gas forms 99 per cent of the whole. These figures are not necessarily final; for some authorities believe that the atmosphere contains an unknown gas lighter than hydrogen, while others think that the hydrogen found in the lower air enters into chemical combinations before it can reach the higher levels; but it is beyond doubt that the composition of the upper atmosphere is quite different from that of the lower.

Of course almost any gas may be found locally and occasionally in the atmosphere, but there are several that are always found wherever a refined analysis of the air is made, and others that are generally present. The following is a fairly complete list: Nitrogen, oxygen, water vapor, argon, carbon dioxide, hydrogen, helium, neon, krypton, xenon, niton (radium emanation), ozone, hydrogen dioxide, ammonia and other compounds of nitrogen.

A number of these substances have only become known to science within the last quarter of a century. Argon, though it constitutes nearly 1 per cent of the atmosphere, escaped detection until the year 1894. The investigation of argon led to the discovery of some of the others. In 1895 it was found that the air, as well as certain minerals, contains helium. This substance was not new to science, but it had never before been found on earth. It was discovered in the atmosphere of the sun, by means of the spectroscope, as early as 1868. Terrestrial helium, neon, krypton, and xenon were all discovered by Sir William Ramsay, who also shared with Lord Rayleigh the distinction of discovering argon.

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