Climatology

“ Cloudiness, as a rule, decreases inland, and with this lower relative humidity, more abundant sunshine and higher temperature, the evaporating power of a continental climate is much greater than that of the more humid, cloudier and cooler marine climate. Both amount and frequency of rainfall, as a rule, decrease inland, but the conditions are very largely controlled by local topography and by the prevailing winds. Winds average somewhat lower in velocity, and calms are more frequent, over continents than over oceans. ”

“ But it would be hard to find any good reason, or any facts of experience, to prove that a professor of history, or an historian, is so much the better the more he knows of geology, oceanography, climatology, and the whole group of geographical sciences. In fact, it is with some impatience, and to no immediate advantage, that students of history work through the courses of geography which their curricula force upon them; and those students who have a real taste for geography would be very glad to throw history overboard. ”

“ The polar limits of the temperate zones are fixed by the isotherm of 50° for the warmest month. Summer heat is more important for vegetation than winter cold, and where the warmest month has a temperature below 50°, cereals and forest trees do not grow, and man has to adjust himself to the peculiar climatic conditions in a very special way. ”

“ Mountain and Plateau Climate.—Both by reason of their actual height and because of their obstructive effects, mountains influence climate similarly in all the zones. Mountains as contrasted with lowlands are characterized by a decrease in pressure, temperature and absolute humidity; an increased intensity of insolation and radiation; usually a greater frequency of, and up to a certain altitude more, precipitation. At an altitude of 16,000 ft., more or less, pressure is reduced to about one-half of its sea-level value. The highest human habitations are found under these conditions. ”

“ While the true basis on which to establish climatic areas or provinces is the resultant of all the weather elements which go to make up the atmospheric conditions recognised under the broader term climate, so many factors have to 185 be considered that it is extremely difficult to arrive at a general acceptable conclusion. The principal elements of the weather to be considered are, approximately, in the order of their importance, beginning with the one which exerts almost universal control—temperature, precipitation, the winds, absolute and relative humidity of the air, and evaporation. ”

“ But the temperature is regulated so much by the position of seas and lakes, in combination with the prevailing currents and strength of currents of the air—by the configuration of the country,—moisture and cloudiness of the atmosphere and quantity of rain,—by the composition, arrangement, and colour of the soil,—by the lower vegetable cover, and even by the nature of the forest itself, whether deciduous or evergreen, that particular facts must be very carefully weighed to enable us to reach general conclusions. ”

“ It is now flourishing in population and science, and after a few more years of observation and collection of facts, they will doubtless furnish a theory of their climate. Years are requisite for this, steady attention to the thermometer, to the plants growing there, the times of their leafing and flowering, its prevalent winds, quantities of rain and snow, temperature of fountains, animal inhabitants, etc. We want this, indeed, for all the states, and the work should be repeated once or twice in a century to show the effects of clearing and culture toward changes of climate. ”

“ The covering of an area by a great city, a village, a forest, a barn, or a tent modifies the climate of the particular area covered so long as the covering remains, but there is no appreciable climatic effect a few feet above the surface of the earth between a forest and a field of grain. The climate of a region like the American continent is controlled fundamentally by the great [244] oceans that wash its shores, by the trend of its mountain systems and their height, and by the direction of its prevailing winds. ”

“ 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. ”

“ But when, on the contrary, a series of changes in the physical geography of the globe, or any other supposed cause, occasions an elevation of the general temperature,—when there is a passage from the winter to one of the vernal or summer seasons of the great cycle of climate,—then the order of the migratory movement is inverted. The different species of animals and plants direct their course from the equator towards the poles; 698 and the northern and southern hemispheres may become peopled to a certain limited extent by identical species. ”

“ Climatic factors include all those relating to atmospheric temperature, rainfall, atmospheric humidity, and light and shade. Factors connected with altitude, aspect, and exposure to winds are also climatic such are often spoken of as physiographical factors. The difficulty of sharply delimiting edaphic and climatic factors is seen in the case of temperature. Soil temperature is partly dependent on the direct rays of the sun, partly on the colour and constitution of the soil, and partly on the water content of the soil. Again, the temperature of the air is affected by radiation from the soil ”

“ The three climatic zones of moderate temperature are described in detail, and the distinctive features of the social condition and civilisation of their inhabitants dwelt upon. The influence of the atmosphere, heat, &c., on the physical and even mental and moral peculiarities of peoples is maintained to be great. Not only the darkness of skin of the negroes, but their characteristics of disposition and of mode of life, are traced to the influence of climate. ”

“ Now, if the Earth of our cold Climate be so fertile of animate bodies, what may we think of the fat Earth of hotter Climates? Certainly, the Sun may there, by its activity, cause as great a parcel of Earth to fly on wings in the Air, as it does of Water in steams and vapours. And what swarms must we suppose to be sent out of those plentifull inundations of water which are poured down by the sluces of Rain in such vast quantities? ”

“ In the regions of Asia, Southern Europe, and Northern Africa, where the weather was at first the most zealously studied, the daily as well as yearly changes of temperature, direction of wind, cloudiness, and precipitation, have a far greater regularity than in our climate.
As Nature there also yields her fruits in greater plenitude, the dependence of universal welfare on the weather phenomena is far less painful and disturbing than in our latitudes. ”

“ It is, upon the whole, not probable that so small an extent of forest, so situated, could produce a sensible influence on the general climate of the globe, though it might appreciably affect the local action of all climatic elements. The total annual amount of solar heat absorbed and radiated by the earth, and the sum of terrestrial evaporation and atmospheric precipitation, must be supposed constant; but the distribution of heat and of humidity is exposed to disturbance in both time and place by a multitude of local causes, among which the presence or absence of the forest is doubtless one. ”

“ The elements—temperature, sunshine, wind, humidity, and rainfall—are recognized as having importance and should be known for every part of our country. The latest movement is for facts in local climate, even that of the farm or certain parts of it, and of the soil. ”

“ In fact, the climate is much more endurable, all the year round, with our refreshing breezes, and particularly in some of the more elevated parts of it, or within one hundred miles of the coast, both in and out of doors, at the South than at the North, which shows most conspicuously the folly of the annual summer migrations, to pursue an imaginary mildness of temperature, which is left at home. ”

“ For the warm atmosphere during the day has dissolved much more water than it can support in solution during the cold of the night, which is thus deposited in large quantities on the hills, and yet so gradually as to soak in between the strata of them, rather than to slide off over their surfaces like showers of rain. The common heat of the internal parts of the earth is ascertained by springs which arise from strata of earth too deep to be affected by the heat of summer or the frosts of winter. ”

“ Next to this north-and-south change, due to climate, we may notice an east-and-west change, due partly to climate, but more perhaps to elimination, for in passing from France to Ireland we have to cross two barriers of sea. The climatic change is not unlike that experienced in going from south to north. We leave a dry climate (rainfall under 25 inches at year) for one of increasing wetness, a warm for a cool summer, a colder for a milder winter. ”

“ We are also to take into account the action of the forest as a conductor of heat between the atmosphere and the earth. In the most important countries of America and Europe, and especially in those which have suffered most from the destruction of the woods, the superficial strata of the earth are colder in winter, and warmer in summer, than those a few inches lower, and their shifting temperature approximates to the atmospheric mean of the respective seasons. ”

“ Enough has been said to indicate that climate is nearly as important to animal life as it is to the vegetable existence, and that a cold climate, if it be not so extreme as to limit the production of cereal crops, and has frequent changes in temperature, pressure, sunshine, and cloud, favors the development of hardy and resourceful races of men; in fact, that no dominating race can exist without such stimulating conditions of climate. ”

“ In its climatological relations the distribution of rain over the globe presents us with a body of facts which lead, when intelligently interpreted, to a knowledge of the laws regulating the distribution of plants more quickly and cartainly than do the facts of temperature. It is to the prevailing winds we must look for an explanation of the rainfall, the broad principles of the connection being these: 1, The rainfall is moderately large when the wind has traversed a considerable extent of ocean ”

“ No factor has a more profound effect in determining the character and distribution of living things than climate, of which the most important elements, for our purpose, are temperature and moisture. One of the most surprising results of geological study is the clear proof that almost all parts of the earth have been subjected to great vicissitudes of climate, and a brief account of the evidence which has led to this unlooked for result will not be out of place here. ”

“ Therefore it may be presumed that definite climatic conditions are required for the specific development of each type of species and for each kind of civilization. Just as history shows that one of the many conditions of human progress has changed repeatedly from century to century on account of variations in climatic factors, so these stimuli have, from the earliest times, swayed and modified all classes of organic life. Climate serves to develop, retard, or extinguish animal characteristics, habits, and development. ”

“ Climate in its modern acceptation signifies that peculiar state of the atmosphere in regard to heat and moisture which prevails in any given place, together with its meteorological conditions generally in so far as they exert an influence on animal and vegetable life. ”

“ Steppes which facilitate the historical movement, and forests which block it, are products of scant or ample precipitation. The zonal distribution of rainfall, with its maxima in the Tropics and the Temperate Zones, and its minima in the trade-wind belts and polar regions, reinforces and emphasizes the influence of temperature in determining certain great cultural and economic zones.
In equatorial regions, which have an abundant rainfall throughout the year, agriculture is directed toward fruits and roots; only in certain districts can it include cereals, and then only rice and maize. ”

“ The word climate has certainly special reference to the character of the atmosphere, but this character is itself dependent on the perpetually concurrent influences of the ocean, which is universally and deeply agitated by currents having a totally opposite temperature, and of radiation from the dry land, which varies greatly in form, elevation, color, and fertility, whether we consider its bare, rocky portions, or those that are covered with arborescent or herbaceous vegetation. ”

“ The one constant characteristic of the climate of this region is its liability at all seasons to frequent and abrupt change, especially by day. It is, as I learned, a rare event when a day passes without one or two, or even more frequent, changes of the wind, bringing corresponding changes of temperature, rain, or snow, or clear sky ”