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The climate of the Alps is the climate, or average weather conditions over a long period of time, of the exact middle Alpine region of Europe. As air rises from sea level to the upper regions of the atmosphere the temperature decreases. The effect of mountain topography on prevailing winds is to force warm air from the lower region into an upper zone where it expands in volume at the cost of a proportionate loss of heat, often accompanied by the precipitation of moisture in the form of snow, rain or hail. The position of the Alps in the central European continent profoundly affects the climate of all the surrounding regions. The accumulation of vast masses of snow, which have gradually been converted into permanent glaciers, maintains a gradation of very different climates within the narrow space that intervenes between the foot of the mountains and their upper ridges; it cools breezes that waft to the plains on either side, but its most important function is to regulate the water supply of the large region which is traversed by the streams of the Alps. Nearly all the moisture that is precipitated during fall, winter, and spring is stored in the form of snow and gradually diffused in the course of the succeeding summer; even in the hottest and driest seasons the reserves accumulated during a long preceding period of years in the form of glaciers are available to maintain the regular flow of the greater streams. Nor is this all; the lakes that fill several of the main valleys on the southern side of the Alps are somewhat above the level of the plains of Lombardy and Venetia, and afford an inexhaustible supply of water, which, from a remote period, has been used for that system of irrigation to which they owe their proverbial fertility. Six regions or zones, which are best distinguished by their characteristic vegetation, are found in the Alps. It is an error to suppose that these are indicated by absolute height above sea level. Local conditions of exposure to the Sun, protection from cold winds, or the reverse, are of primary importance in determining the climate and the corresponding vegetation. ==Subalpine region== The Subalpine is the region which mainly determines the manner of life of the population of the Alps. Roughly one quarter of the land lying between the summits of the Alps is available for cultivation. Of this low country, about one half may be vineyards and grain fields, while the remainder produces forage and grass. Of the high country, about half is utterly barren, consisting of snow fields, glaciers, bare rock, lakes and stream beds. The other half is divided between forest and pasture, and the product of this half largely supports the relatively large population. For a quarter of the year the flocks and herds are fed on the upper pastures, but the true limit of the wealth of a district is the number of animals that can be supported during the long winter, and while one part of the population is engaged in tending the beasts and in making cheese and butter, the remainder is busy cutting hay and storing up winter food for the cattle. The larger villages are mostly in the mountain region, but in many parts of the Alps the villages stand in the subalpine region at elevations varying from 1200 m to 1700–1800 m (4000–6000 ft). The most characteristic feature of this region is the prevalence of coniferous trees that, where they have not been removed, form vast forests that cover a large part of the surface. These play a most important part in the natural economy of the country. They retain the soil by their roots, protect the valleys from destructive avalanches and mitigate the destructive effects of heavy rains. In valleys where they have been cut away, waters pour down the slopes unchecked; every tiny rivulet becomes a raging torrent that carries off the grassy slopes and devastates the floor of the valley, covering the soil with gravel and debris. In the conifer forests of the Alps the prevailing species are the Norway spruce and the silver fir; on siliceous soil the European larch flourishes. The Scots pine is chiefly found at a lower level and rarely forms forests. The Swiss pine is found scattered at intervals throughout the Alps but is not common. The mountain pine is common at higher altitudes, often forming a distinct zone of Krummholz above the level of its congeners on the higher mountains. In the Northern Alps the pine forests rarely surpass 1800 m (6000 ft) elevation, but on the south side they commonly attain 2100 m (6900 ft), while European larch, Swiss pine and mountain pine often extend above that elevation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Climate of the Alps」の詳細全文を読む スポンサード リンク
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