The time distance between the most western and eastern points is 11 hours. The ninetieth meridian of east longitude may be regarded as the central meridian, and the fortieth parallel of north latitude as the central parallel of the continent. These lines of orientation cut one another near Lob Nor, in eastern Turkestan.
This enormous continental mass, with the exception of a territory in the extreme northeast, about as large as the area of England, lies in the northern division of the Eastern Hemisphere, while its islands extend on the southeast across the Equator. On three sides it is surrounded by the ocean, but on the west it joins Europe, the line of separation between them being accepted as the Ural Mountains, an irregular line from their south end to the north end of the Caspian Sea, thence the Caucasus Range to the Black Sea.
By the Isthmus of Suez Asia has a connection with Africa, from which it is separated by the narrow Red Sea, occupying a rift valley of comparatively recent formation. The continent has an average elevation above the sea of over 3000 feet. The coast line is about 33,000 miles in length, and on the south and east is greatly diversified by seas, bays, and gulfs, affording advantages to navigation and commerce far superior to those of Africa and South America, but inferior to those possessed by Europe and North America. The indented and broken northern coast is, to some extent, available for navigation in the summer months from Waigat Strait, south of Nova Zembla, to the Obi and Yenisei rivers; and in 1912 and 1913 Russian survey vessels steamed along the northern coast from Bering Strait to Cape Chelyuskin; but the whole north coast is icebound most of the year.
Asia is bounded northward by the Arctic Ocean, into which its continental shelf, covered to depths of only 600 feet, penetrates far to the north, eastward by the Pacific Ocean, southward by the Indian Ocean, and westward by Europe, the Caspian Sea, the Black Sea, the Mediterranean, and the Red Sea. On the extreme northeast it is separated from North America only by the narrow Bering Strait, about 40 miles wide. On the southeast the vast eastern archipelago, comprising numerous great islands, Luzon and Mindanao in the Philippines, Sumatra, Borneo, Java, Celebes, New Guinea, and hundreds of smaller ones, extends almost to Australia.
The body of the continent may be regarded as a trapezium, of which the projections, consisting of several large peninsulas, bear some resemblance to those of Europe, though in Asia everything is on a greater scale. On the west is the peninsula of Asia Minor, or Anatolia, separated from Europe by the Bosporus, the Sea of Marmora, and the Dardanelles, with the Black Sea on the north, the iEgean Sea on the west, and the Levant (the easternmost part of the Mediterranean) on the south. On the south of Asia Arabia may be considered as a counterpart of the Iberian Peninsula; Italy, with its neighboring island, Sicily, is represented by India and Ceylon; and as the broken Grecian Peninsula in Europe has numerous islands extending toward Asia on the southeast, so in Asia the Malay Peninsula has an island connection with Australia on the southeast by means of the Eastern Archipelago.
The eastern coast of Asia is characterized by the deep indentations made by the Pacific Ocean, forming the South China Sea on the southeast, and the Yellow, East China, Japan, Okhotsk, and Bering peas on the east, all island-bound, and separated from the Pacific respectively by the Philippines, the Liu-Kiti Islands, Korea, Japan, and Kamchatka. On the north the Siberian coasts are also deeply indented, but rather by the embouchures of large rivers than by arms of the eea.
The seven great river systems of Asia are: the Mesopotamian, that of northwest India, that of northeast India and Tibet, the Indo-Chinese, the Chinese, the Siberian, and that of the Kirghiz steppe and Russian Turkestan. The first comprises the two famous streams, the Tigris and Euphrates, flowing into the Persian Gulf; the second comprises the Indus with its tributaries; the third system comprises the Brahmaputra and Ganges; the fourth comprises the rivers of the Indo-Chinese Peninsula, the chief of which are the Irawadi, the Salwen, the Menam, and the Mekong; the fifth system is the Chinese, comprising four great streams, all of which flow in a general easterly direction into the Pacific—the Si-kiang, the Yang-tzi-kiang, the Hoang-ho, and the Amur; the sixth system comprises the large rivers of Siberia, the principal of which are the Obi, the'Yenisei, and the Lena—all have their source in the ranges bordering Siberia on the south and flow northward, traversing the great plain for 800 or 900 miles before their sluggish waters reach the Frozen Sea; the seventh system comprises the Ural, which flows into the Caspian Sea, and several other inland rivers, including the Amu-Darya and the Syr-Darya, flowing into the Aral Sea, the Hi, which flows into Lake Balkash, and the Tchui.
Asia has a great variety of climate, owing to its range of latitude, altitude, and its relations to the bordering seas. It is in the main a continental climate, with light rainfall, a dry atmosphere, and great extremes of temperature. Near the coasts the climate is modified by the proximity of the sea, but this influence extends but a short distance inland, as the prevailing winds are off the land, except in the south, and even there the contrary is the case only during the prevalence of the monsoons. The whole of northern Asia lies within the range of the prevailing westerly winds of the Northern Hemisphere, in which are found the extensive cyclones and anti-cyclones which give variability to the weather in temperate latitudes. On the eastern and southeastern coasts cyclones of the hurricane type originate in the region of the tropical islands, and, pursuing a course at first westerly, under the influence of the trades, gradually turn toward the north and east, often ravaging the coast to some distance inland. In the extreme southern part of Asia occur general storms of hurricane character and local storms of the tornado form.
Asia is deficient in lakes. At the base of the ranges limiting Siberia on the south, are, however, several of magnitude, among them Baikal, believed to be the deepest fresh-water lake in the world, Balkash, and Issyk-kul. Farther west, in the depression east of the Caucasus, are the Aral and Caspian seas, which have no outlet; the Caspian Sea is 85 feet below the level of the sea. In Syria is the Dead Sea, occupying with its valley a deep depression, the surface of the lake being about 1300 feet below sea level. In the Armenian Mountains are lakes Van and Uramia, lying at great elevations and having no outlets. In Tibet and the desert of Gobi lakes without outlets are numerous, since, owing to arid conditions, drainage systems are not yet developed. A large part of Asia, comprising Tibet, Mongolia, Turkestan, and most of Baluchistan, Persia, and Arabia, i.e., nearly all the central and southwestern parts of the continent, the region in which the rainfall is deficient, has no drainage to the sea.
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