Weather map

“ The great areas of high and low pressure control our weather. On land, where daily weather maps are so easily accessible, a glance at the map serves in most cases to give a fairly accurate idea of the position and extent of cyclones and anticyclones, and hence also of the distribution of weather. At sea, on the other hand, the navigator has no daily weather maps to refer to, and his knowledge of the weather conditions which he may expect must be gained from his own observations alone. ”

“ By preserving the weather map 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 towards him, 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 fair weather, except during periods of extreme summer heat, when the Lows bring showers that cool the parched earth ”

“ The Weather Bureau does not possess on its books the record of any two days when the weather was duplicated over the United States."
"You mean that every day's weather map is different?"
"As different as every human face," the Forecaster replied, "and to those of us who have done much forecasting, it is as easy to see from the map when the weather is going to be peaceful or stormy as it is to tell whether a man is smiling or scowling. But let us look at these three charts closely, and you will see just why Fred was right. ”

“ Coast-wise and lake shipping are therefore not only affected by the forecasts made by the Weather Bureau but by the forecast made by the masters themselves when they can get access to the daily weather map. Their own lives and the lives and property of others are in their keeping. But the great mass of intelligent people have no idea of the methods employed in the making of the weather map and of the many and widely diversified uses to which a study of its data would lead. ”

“ Almost every daily paper publishes a résumé of the weather map; some reproduce the map itself. All told, the daily forecast is so widely published that it is within almost instant reach of everyone within the main body of the country. ”

“ The weather map of the United States is based on simultaneous observations made at about 150 stations in different parts of this country, besides several coöperating stations in Canada, Central America, Mexico, and the West Indies. At each of our stations, whose48 location may be seen on any weather map, the Weather Bureau employs one or more observers, who, twice a day, at 8 A.M. and 8 P.M., “Eastern Standard Time,” make regular observations of the ordinary weather elements, i.e., temperature, pressure, humidity, wind direction and velocity, precipitation, cloudiness, etc. ”

“ The aviator is not concerned with the forecast of the morrow’s weather, unless he is making an unusually long flight, but he is immensely concerned with the winds and weather prevailing along his route at the time he flies, and these will not, as a rule, differ radically from the conditions shown on the map of the same morning.
Since weather affects business in a variety of ways, people who have business interests away from their places of residence frequently have occasion to consult the weather map. ”

“ It was then discovered that a certain type of weather map preceded such failures of the forecaster. One who is interested in gaining early knowledge of the approach of a cold wave to the United States should watch not only for the appearance of abnormally high barometer readings, from the stations of the Canadian Northwest, or from Montana and North Dakota, but especially for a crescent-shaped Low, with one horn of the crescent touching Lake Superior and the other extending into the middle Rocky Mountain region, at about Colorado. ”

“ So also all observers not on the meridian of New York would more or less mis-locate the center. Since nearly all cyclones and anti-cyclones move from east to west or from west to east, and very few in a meridional direction, the systematic misrepresentation of their relative positions in point of longitude works grave defects. A weather-map based on such non-simultaneous reports, instead of faithfully mirroring the sky overhanging a continent, necessarily gives it rather a wry face. Even at this date, we can not say that all European weather-stations take observations simultaneously. ”

“ Manuscript maps prepared daily at Washington have a still broader outlook; they are drawn on a base map that covers the northern hemisphere, and the printing of a map of this sort, including a chain of stations extending around the globe, was undertaken in 1914, but was interrupted by the war. The map published by the Argentine Meteorological Office, at Buenos Aires, covers more than half of South America. Most national meteorological services issue weather maps, but there are a few that do230 not. ”

“ An examination of the weather map when a northeast storm is in progress will show that the center of the disturbance is southwest or west of the observer, the winds backing to northwest when the center subsequently passes close by or south of the point of observation in its easterly or northeasterly movement.
The tradition that the climate of a city is very different from that of the surrounding country, while partially true, is often exaggerated in the public mind. ”

“ The influence of the weather on crops explains why the map is watched with keen interest by dealers in agricultural products. Owners of vessels navigating the ocean or the Great Lakes take a practical interest in the present as well as the future location of storms. And so on. It is not necessary to prolong this list of those who use the weather map, because the popular demand for it speaks for itself. It is worth while to record the fact that the demand far exceeds the supply. ”

“ Owing to the very mobile nature of the atmosphere, the changes taking place on one portion of the globe, especially in the Arctic zone, quickly affect regions very distant therefrom. The study of the weather in Europe and America can not be successfully prosecuted without a daily map of the whole northern hemisphere, and the great blank space of the Arctic region upon our simultaneous international chart has long been a subject of regret to meteorologists. ”

“ No meteorologist in the modern sense attempts to forecast the weather without reference to a map prepared either by himself226 or by some one with whom he is in direct communication, from observations transmitted by telegraph for the purpose. No amount of weather wisdom or weather lore or experience is a substitute for the map. ”

“ The principal elements of the weather which go to make up the conditions of the atmosphere embraced in the broader term climate are temperature, precipitation, and the winds. On the accompanying map, Plate II, the mean annual temperature of the continent is represented by isotherms, or lines drawn through localities having the same average temperature for the year. On the same map is also shown in blue the average depth of precipitation, including both rains and melted snow. ”

“ In order to carry on this work properly, numerous stations must be connected by telegraph with the central bureau, at which several simultaneous observations must be received daily from the observers, and weather charts must be promptly made out showing the isobars, isotherms, state of the wind and weather, moisture and clouds over a large region of country. The accompanying charts, for April 3d, 8 A.M., and 4th, 8 A.M., 1892, show the general character of such daily weather maps; they will easily be understood by studying the respective legends. ”

“ In this country the publication of weather maps has been carried out on a much more liberal scale than elsewhere. Instead of issuing maps at only one or a few places, as is the custom in other parts of the world, it has been the policy of the American service to publish them at populous centers all over the country. ”

“ With the principles of this science all the more reliable rules of weather-forecasting are most intimately connected. We no longer think of judging of coming weather merely by the aspect of the sky and an examination of an individual barometer. We invariably refer—I do not say to the weather-reports of a few hours previous, for we often have neither these nor any weather-reports at all at hand—but we invariably refer to rules already deduced from the long study of weather-maps. The man who ignores these rules had better, in my opinion, leave all attempts at weather-forecasting alone. ”

“ The artificial temperature of a city street is too local and indefinite a thing to be inscribed on weather maps, utilized by the forecaster, or embodied in climatic statistics. As a concession, however, to the demand of the “man in the street” for a record of conditions prevailing in his own sphere,75 the Weather Bureau has installed in several cities little pavilions in which working meteorological instruments are displayed for the benefit of the public. ”

“ At best his weather-lore will not rise much above that of the bees, which fly to the hive, often to their own detriment, whenever a dark cloud covers the sun." We cite these words as expressive of the wise dependence which the most skillful European meteorologists put upon the weather-charts of the past. How much more light will they derive from the new international "simultaneous" weather-maps! ”

“ The cooperative observer can do much to aid in establishing definite facts on which predictions may be made. Among them and of first importance is establishment of the direction of rain-winds. These, as has been shown, are easterly winds, but conditions of topography may change the real direction to one that is apparent. The apparent direction should be established for each month in the year. In every community there are weather-wise people who possess valuable information that they have not recorded. ”

“ Rapidly falling barometer, rising temperature, and light southerly winds indicate rain or snow, according to season of year.
Falling barometer, rising temperature, with wind from northeast or east, indicate snow.
Fine cirrus and cirro-stratus, floating low, presage wind.
Haze in night or early morning, or cumulus clouds, sharp and well defined, moving from west or southwest, indicate fair weather.
When snow is falling, and the wind backs from east to north, with decreasing velocity, clear weather may be expected. ”

“ It is from similar maps that forecasts of storms are still framed, and suitable warnings issued; and a mass of information is being collected by telegraph from sixty stations in the British Islands, &c., of the state of the weather at eight o’clock every morning, and analysed and arranged at the Meteorological Office in London for the evening’s forecasts over the different districts of the country. A juster knowledge is being now acquired of those great atmospheric movements, and other changes, which form the groundwork of weather-forecasting. ”

“ In winter, after the prevalence of easterly winds, if the barometer begins to fall and the thermometer to rise, a gale which commences to blow from the southeast will veer to southwest, while the barometer falls constantly. As soon as the wind passes the southwest point the barometer begins to rise, a heavy shower of rain falls, and a strong west-northwest or northwest wind may follow, after which the sky clears and the weather becomes colder. ”

“ The barometer rises for northerly winds, including from northwest by north to the eastward for dry or less wet weather, for less wind, or for more than one of these changes, except on a few occasions, when rain, hail, or snow comes from the northward with strong wind. ”

“ It is believed that a further discussion of meteorological phenomena on a broad basis, by means of International Weather Charts, both in daily and monthly form, must eventually result in important and fundamental discoveries. It is gratifying to American pride to know that in this international task of outlining the geography of the air, the United States has liberally provided the labor and means for presenting these ten years' meteorological data in such tabular and geographical forms as to render them available for study by all. ”

“ As a whole, the portion of the continent embraced in the temperate zone is characterized by its pronounced seasonal changes, including wide extremes of heat and cold over large areas, and by its frequently sudden and strongly marked weather changes during short periods of time. It is a highly suggestive fact that of all the great climatic zones the one having the most changeable climate, the greatest extremes of heat and cold, and the most frequent storms should be the one in which man has reached the highest development both of body and mind. ”

“ The next year an atlas, with coloured pictures of the clouds, separated according to the new nomenclature, with descriptive text, was prepared by Dr. Hildebrandsson, assisted by Drs. Neumayer and [Pg_43] Köppen of the Deutsche Seewarte, or German National Meteorological Observatory. This atlas was adopted by the principal meteorological institutions on the continent of Europe for their observers. The preface contained the following statement: "The study of the forms of clouds is daily increasing in importance, both from the standpoints of theory and of weather prediction. ”

“ What produces the extra-tropical belt of regular rains surrounding the earth, north of the parallel of 30° north, in some places, and 35° in others, extending to the pole, with its southern edge traveling up ten or more degrees in summer, leaving large portions of the earth subject to a dry season; and back again in the winter to give them a rainy one? What produces the narrow belt of inter-tropical rains, encircling the earth; traveling up and down every year over an average of 35° of latitude, supplying every portion of it alternately with rain? ”