V.—CLIMATE.
The influence exercised by the relief of the land and the configuration of the coasts varies in different ages, but that of climate is permanent. In this respect Europe is the most favoured region of the earth, for during a cycle of unknown length it has enjoyed a climate at once the most temperate, the most equable, and the most healthy of all continents.
Owing to the inland seas which penetrate far into the land, the whole of Europe is exposed to the modifying influence of the ocean. With the exception of Central Russia, no part of Europe is more than 400 miles from the sea, and, as most of the mountains slope from the centre of the continent towards its circumference, the influence of the sea breezes is felt throughout. And thus continental Europe, in spite of its great extent, enjoys the advantages of an insular climate throughout, the winds passing over the ocean moderating the heat of summer and tempering the cold of winter.
The continuous north-easterly movement of the waters of the Atlantic likewise has a favourable effect upon the climate of Europe. After having been heated by a tropical sun in the Gulf of Mexico, the gulf-stream issues through the Strait of Florida, and, spreading over the Atlantic, takes its course towards the coasts of Europe. This enormous mass of warm water, equal in volume to twenty million rivers as large as the Rhone, brings the warmth of southern latitudes to the western and northern shores of Europe. Its influence is felt not only in the maritime countries of Western Europe, but to some extent as far as the Caspian and the Ural Mountains.
The currents of the air exercise as favourable an influence upon the climate of Europe as do those of the ocean. The south-westerly winds predominating on the coasts pass over the warm gulf-stream, and, on reaching Europe, they part with the heat stored up by them between the tropics. The north-westerly, northerly, and even north-easterly winds, which blow during a portion of the year, are less cold than might be expected, for they, too, have to cross the warm waters of the gulf-stream. And lastly, there is the Sahara, which elevates the temperature of a portion of Europe.
The increase in temperature due to the combined influence of winds and ocean currents amounts to 40° 50°, and even 60°, if we compare Europe with other parts of the world lying under the same latitudes. Nowhere else, not even on the western coast of North America, do the isothermals, or lines of equal annual temperature, ascend so high towards the arctic regions. The inhabitants of Europe, though they may live 900 to 1,200 miles farther away from the equator, enjoy as mild a climate as do those of America, and the decrease of temperature on going northward is far less rapid than in any other part of the globe. This uniformity of temperature constitutes one of the most characteristic features of Europe. The whole of it lies within the temperate region bounded by the isothermal lines of 32° F. and 68° F., whilst in America and Asia that privileged zone has only half this extent. {17}
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Fig. 4.—THE ISOTHERMAL ZONE OF EUROPE.
Scale 1 : 60,000,000.
This remarkable uniformity in the climate of Europe is exhibited not only in its temperature, but likewise in the distribution of its rains. The seas washing the shores of Europe supply all parts of it with the necessary amount of moisture. There is no rainless district, nor, with the exception of a portion of the maritime region of the Caspian and a small corner of Spain, any district where droughts occasionally entail the entire loss of the harvest. Rains fall not only regularly every year, but in most countries they occur in every season, the only exception being the countries of the Mediterranean, where autumn and winter are the real rainy seasons. Moreover, in spite of the great diversity in the physical features of Europe, the amount of rain is scarcely anywhere excessive, whether it descends as a fine drizzle, as in Ireland, or in heavy showers, as in Provence and on the southern slope of the Alps. The annual rainfall scarcely ever exceeds thirty-nine inches, except on the flanks of certain mountain ranges which arrest the passage of currents charged with moisture. This uniformity and moderation in the rainfall exercise a regulating influence upon the course of the rivers, for even the smallest amongst them, at all events those to the north of the Pyrenees, the Alps, and the Balkan, flow throughout the year. They rise and fall generally within narrow limits, and inundations on a vast scale are as rare as is want of water for purposes of irrigation. In consequence of this regularity, Europe is able to derive a greater advantage from its waters than other continents where the amount of precipitation is more considerable. The Alps contribute much towards {18} maintaining a regular flow of the rivers; the excess of humidity which falls to their share is stored up in the shape of snow and ice, which descend slowly into the valleys, and melt during the heat of summer. This happens just at a time when the rivers gain least from rain, and lose most by evaporation, and some amongst them would dry up if the ice of the mountains did not come to the aid of the waters descending from the sky. It is thus that a sort of balance is established in the economy of European rivers.
The climate of Europe is thus characterized by uniformity as a whole, and by a compensatory action in its contrasts. Regularity and freedom from excess, such as are not known in other continents, mark its ocean currents, its winds, its temperature and rains, and the course of its rivers. These great advantages have benefited its inhabitants in the past, and will not cease to do so in the future. Though small in extent, Europe possesses by far the largest area of acclimation. Man may migrate from Russia to Spain, or from Ireland to Greece, without exposing himself to any great risk of life. The inhabitants of the Caucasus and the Ural Mountains were thus able to cross the plains and mountains of Europe, and to establish themselves on the shores of the Atlantic. Soil and climate are equally propitious to man, and enable him to preserve his physical and intellectual powers wherever he goes. A migratory people might found new homesteads in any part of Europe. Their companions of travel—the dog, the horse, and the ox—would not desert them on the road, and the seed-corn which they carry with them would yield a harvest wherever confided to the earth.
