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18 MARINE REVIEW. THE SCIENCE OF STORMS. BY WILLIS L. MOORE, CHIEF OF TH At about 100 miles from the surface of the earth there is only re hypothetical ether which, while too tenuous to be detected or measure 7 any appliance known to man, is supposed to transmit the solar ee energy. This energy, coming in many different wave lengths, and wit widely differing velocities of vibration, produces a multitude of phenomena as it is absorbed or passes through our air, or as it impinges upon the surface of the earth. The longer and slower waves are convertible into heat, the shorter and more rapid ones into light, and the minutest move- ments, probably into electricity. The air, even at the surface of the earth, is not dense enough to absorb and convert into heat much of this solar energy, and therefore the earth receives it, is itself warmed on the surface and in turn radiates back into the air, in such condition of wave-length and velocity of vibration that the air can absorb it, most of the heat that the air receives. The atmosphere is thus warmed from the bottom up- wards. This accounts for the perpetual freezing temperatures of very high mountain peaks, although they are nearer the sun than are the bases from which they rise. At the height of 100 miles the temperature must be about that of outside space, probably 459 degrees Fahrenheit below zero. in the gaseous state in a region having a lower temperature. When it is liquefied it has the color and general appearance of water, and about the same specific gravity. When a piece of steel and a lighted taper are brought together inside of a vessel filled with liquid air the dense supply of oxygen makes combustion so rapid that the hard metal burns like tinder. At the height of 50 miles there is enough air to slightly refract light at twilight and to render luminous the meteors that rush with fearful velocity against the widely scattered molecules. But at this distance from the earth there probably is no more air than would be found under the receiver of the best of air pumps. At the height of about 25 miles the air, light as it is, has still sufficient density to obstruct the passage of the minutest wave-lengths of light. Here may be developed the electro-magnetic energy which, in extreme nerthern and southern latitudes, is manifested in the auroras. Here also begins to be appreciable the blue tint of the heavenly vault. At the height of 10 miles the temperature is unchangeable from winter to summer, and not less than 60 degrees below zero. At this short dis- tance from the earth there is a death-like stillness, for there is no medium sufficiently dense to transmit sound. Two persons could not hear each cther speak, even if they could live in this rare atmosphere, which they cauld not. . Here is eternal peace and no apparent motion, for storms and ascending and descending currents cease long before they reach this level. At the height of 6 miles the cirrus clouds common to this level are, ou account of the low temperature, always composed of minute ice spicule--never of watery droplets--and in the middle latitude of both hemispheres the air at this height is ceaselessly rushing toward the east, passing uninterruptedly over the cyclonic and anti-cyclonic systems that constitute our storms and cold waves at the surface of the earth. Glaisher ascended to this height, but he became insensible by asphyxiation, and his assistant retained consciousness only by breathing liberated oxygen. They were nearly destroyed by the cold which registered many degrees below zero, although the time of year was Sept. 5. The dry air at the surface of the earth is a very poor conductor of electricity, but the same air reduced to the low density found at the six- miile level is a wonderfully good conductor. It is this condition of the upper air that Tesla claims he may be able to take advantage of in trans- mitting electric power to a great distance without the use of a metallic medium. -- : Air is so elastic and its density decreases so rapidly as it recedes from the earth that nearly one-half of the entire mass of air lies below the level of the top of Pike's peak, which has a height of little less than 3 miles above sea level. At the height of 1 mile the temperature is about the same at midday as at midnight. : Only during very recent years have we begun to realize how ex- tremely thin is the stratum of air next to the earth that has sufficient heat and moisture for the inception, 'growth and maturity of animal and vege- table life. The raising of the instrument shelter of the New York city observatory from an elevation of 150 ft. above the street to an elevation of 300 ft. has caused an apparent lowering of the mean annual temperature of 2% degrees. On the hottest days in summer if one could be lifted up to a height of 1,000 ft. in free air he would find a temperature so cool as to be pleasant and conducive to bodily vigor. : Any intelligent person, by studying the few simple principles on which the daily weather map is founded, can make an intelligent estimate of the general chatacter of the weather, for his region one, two, and, at times, three days in advance. You may ask: Why has not this been done by the laymen whose crops, whose perishable produce in transit, whose vessels exposed to the fury of wave and tempest, and whose health and pleasure are so dependent upon the weather and upon the sequence in which weather changes occur? In answer it'may be said that many members of commercial associations knowing the fluctuations in value of soil products that often result when rain falls on a parched district, when frost smites the corn in the milk when hot south winds wither the crops in the great central valleys or when clouds and moisture affect the condition of cotton, make a fairly accurate forecast of the weather from the large daily weather maps dis- played on blackboards before all the important commercial exchanges of the country, and in a pecuniary way largely profit therefrom. This morning at 8 o'clock Washington time (which, by the way, is about 7 o'clock in Chicago, 6 o'clock at Denver, and 5 o'clock at San Francisco) the observers at 200 stations in the United States and con- tiguous territory were taking their observations, and from carefully tested and standardized instruments noting all the elementary conditions of the air at the bottom of the great aerial ocean in which we live. *An address before the Manufacturers' Club of Philadelphia, Air liquefies at 312 degrees below zero, and, therefore, it cannot exist | --E UNITED STATES WEATHER BUREAU.* -20 a. m. the barometers have been reduced to sea level, so th Cou de to local altitudes may not a and obscure those due . storm conditions, the necessary eather cones made, the ob. servations reduced to cipher form, and each report has been filed at the local telegraph office. During the next tory ee the observations, with the right of way over all lines, are speeding to their destinations, each station contributing its own observation and receiving in return, by the workings of an ingenious system of telegraph circuits, such obserya- tions from other stations as it may require. | The observations from all stations are received at such centers as Washington, Chicago, New York and other large cities, and nearly all cities having a weather bureau station receive a sufhcient number of reports from other cities to justify the issy. i a weather map. oe ing es picture in ie mind that all the air inside the isobar marked 30.2, as it moves inward, is rotating about the "low" in a direction con- trary to the movement of the hands of a watch, and you have a very fair - conception of an immense atmospheric eddy. Have you ever watched the placid waters of a deep running brook and observed that where it encountered a projecting crag little eddies formed and went spinning down the stream? Well, our storms are simply great eddies in the air that are carried along by the general easterly movement of the atmosphere in the middle latitudes of the northern hemisphere. But they are not deep eddies, as was once supposed. The "low" marks the center of an atmospheric eddy of vast horizontal extent as compared with its thickness or extension in a vertical direction; thus a storm condition extends from Washington to Denver in a horizontal direction and yet extends upwards but 4 or 5 miles. The whole disk of whirling air 4 or 5 miles thick and 2,000 miles in diameter is called a cyclone, or cyclonic system, or a low-pressure area. It is important that a proper conception of this fundamental idea be had, since the weather sequences, experienced from day to day, depend almost wholly upon the movement of these travel- ing eddies, cyclones, or areas of low pressure. The foregoing are a few of the generalizations of which the forecaster takes cognizance and that guide him in his deductions. In brief, he care- fully notes the developments and movements in the air conditions during the preceding twenty-four hours, and from the knowledge thus gained makes an empirical estimate of what the weather will be in the different sections of the country the following day. By preserving the weather charts each day and noting the movements of the highs and the lows, any intelligent person can make a fairly accurate forecast for himself, always remembering that the lows, as they drift toward him from the west, will bring warmer weather and sometimes rain or snow, and that as they pass his place of observation the highs following in the tracks of the lows will bring cooler and probably fair weather, He can closely forecast the temperature for his region by remember- ing that the weather will be cool so-long as the center of the predomi- nating high, i. e., the high inclosing the greatest area within the 30-in. isobar, is north of his latitude--either northeast or northwest, and that it will be warm so long as-the high is south of his latitude. West Indian hurricanes are cyclonic in character, but on account of the fact that the diameter of the whirling eddy is much less and the ve- locity of rotation much greater than in the average cyclone that crosses our continent, it is customary to designate them as hurricanes. In other words, the hurricane is a cyclone of small area but . powerful vortical action, and consequently of great destructive force. To get a rough idea of the difference between storms, we might classify them according to.the diameter of the gyrating masses of air under their influence, as follows: Cyclones, 1,000 to 2,000 miles; hurricanes, 100 to 500 miles; and torna- does 100 to 1,000 ft. We might imagine their vortical action and their destructive force to increase in some ratio as their diameters of rotation decrease. , is The tornado is always an incident and a sporadic outbreak of the cyclone and usually occurs in the southeast quadrant of a cyclonic storm. The thunderstorm, instead of rotating about a vertical axis, like the cyclone and tornado, has a horizontal roll, caused by cold and heavy air from above breaking through into a lighter and super-heated stratum next © to the earth: This rolling motion throws forward the cool air in the direction in which the cloud is moving. . In general, thunderstorms move from the west toward some eastern point, the same as tornadoes, which mostly move from the southwest toward the northeast. If any part of the horizontally-rolling air in the thunderstorm drops down toward the earth -- and adjusts its rotation about a vertical axis it at once becomes a tornado, and its destructive force is increased a hundred fold. Thunderstorms are seldom more than 5 or 10 miles in width, and their tracks are not often more than 20 or.30 miles in length. There is a close relation between the conditions of air that produce thunderstorms and those that produce tornadoes. _ The staff of the weather bureau, which includes many able meteorolo- gists, has not failed to make a study of the peculiarities of the several types of storms occurring in different localities during the various seasons of the year, their lines of travel, and the force they may be expected to attain. The comparative merits of those who, by education and natural ability, were the best fitted to correctly and quickly correlate in their minds the conditions shown on a meteorological chart and to make accurate de- ductions therefrom as to the development, movement and force of storms, have been tested by competitive examinations. This line of study and competition has resulted in improved forecasts, so that mariners now universally heed the storm warnings, horticulturists make ample provisions against frost, and shippers of perishable produce give full credence to the cold wave predictions. Of the many West Indian hurricanes that have swept our Gulf and Atlantic seaboard during recent years, not one has reached a single seaport without danger warnings hav- ing been sent well in advance of the : storm, and few unnecessary warnings have been issued. The result is t a curred. * Large owners of marine : i : oe Property estimate that one severe storm pavers our Atlantic coast in the absence of danger warnings would eave not less than $3,000,000 worth of wreckage. On two occasions @ census was taken immediately after the passage of severe hurricanes' to de- hat few disasters of consequence have OC