General : There are seven continents of which Asia is the largest in the world. It has an area of 44.6 million sq. km and covers about 33% of land surface of the world. The population of this continent is 3686 million people. Asia has about 60% of world population, It is the most populous continent.
Special features of the Continent
Asian countries have greatest diversity in terms of climate, vegetation, wildlife and people. Special features are :
(i) Asia has the highest mountain peak on the Earth, Mount Everest (8848 m) and the lowest point, the Dead Sea (400 m below Sea level)
(ii) Verkhoyansk in Siberia is the coldest place in Asia. Its temperature in winter goes to –700C.
(iii) Jacobabad in Sindh is the hottest place on the earth.
(iv) Maysinram and Cherrapunji in India has the highest rain fall of 2600 cm per year.
(v) The worlds deepest fresh water lake namely Baikal lake is in Asia. Its depth is 1637 metres.
(vi) Sunderbans is the largest delta.
(vii) It has the most fertile valleys of Ganga, Indus, Brahmaputra etc.
(viii) Asia has the largest barren land of Baluchistan.
(ix) It has the rich and varied wild life.
(x) This continent has been the cradle of ancient civilizations, Indus, Chinese Mesopotamian etc.
(xi) Asia has been the birthplae of many religions of the world such as Judaism, Hinduism, Christianity, Jainism, Sikhism, Buddhism, Zorastirianism etc.
Asia has the following 46 countries :
Location of Asia
Asia continent is in the Northern Hemisphere.
(i) Latitude : It is between 100S to 800 N latitudes.
(ii) Longitude : It is in the Eastern Hemisphere and extends from 250E to 1700E. This big longitudinal range brings about a difference of 11 hours between the local times of the easternmost part and the westernmost part of Asia.
(iii) Boundaries : This continent has oceans on three sides—Arctic Ocean in the north, Pacific Ocean in the east and the Indian Ocean in the south. In the west, it is separated from Europe by Ural mountains, the Ural river and the Caspian Sea. The Red Sea and the Suez Canal separate it from Africa. On the north-east side, the Bering Strait separates it from North America.
(iv) Coastline of Asia : The Asian coastline has several bays, seas and gulfs.
(a) Along the east coast, Asia has the China Sea, Yellow Sea and the Sea of Japan.
(b) In the north-east, Asia has Sea of Okhotsk and Bering Sea.
(c) On the south side, we have the Arabian Sea and Bay of Bengal.
(d) Asia on the west, has Persian Gulf, Gulf of Aden and Red Sea.
Physical Divisions of Asia
Asia is divided into five physical parts :
1. Central Mountain belt, 2. The Northern lowlands, 3. The Southern plateaus, 4. The great river valleys, 5. The chain of islands off the coast.
(i) The Central Mountain Belt : This belt is the highest area of mountains and plateaus. The mountain ranges start from the Pamir Knot situated of India. The Great Himalayas and the Karakoram radiate to south-east from the Pamir Knot. The Hindukush range goes to the west of the Pamir. The Kunlun range and the Tien Shan is continued by the Altai and the Yablonovy ranges. The Hindukush and Suleman ranges go westwards by the mountain ranges of Iran and Iraq. The mountain mountains enclose a number of high plateaus. The plateaus of Tibet, Gobi desert, the Tarim basin, Mongolia, Plateau of Iran, Anatolia plateau in Turkey are the plateaus located between mountain ranges.
(ii) The Northern Lowlands : The Northern lowlands lie in the north of Central Mountain Belt. This belt consists of two subdivisions. The northern part is known as the Great Siberian Plain which is drained by the Ob, Yeniseiy and Lina rivers. During the beginning of the summer, snow melts in the upper courses of these rivers, while the lower portions remain frozen. Water stagnates over a large area forming marshes and swamps.
South of Siberian plains are located in the lowlands of Central Asia. The Caspian and the Aral sea are two large inland seas.
(iii) The Southern Plateau : The southern plateaus are made of old, hard crystalline rocks. There are three plateaus.
(a) The Plateau of Arabia : Arabia plateau has a steep slope on the west facing the Red Sea and slopes to north-east, passing into the Tigris valley.
(b) The Deccan Plateau of India : The Deccan plateau has a steep slope on the west, known as the Western Ghats. The plateau slopes to the east. The low eastern edge is formed by the Eastern Ghats. This plateau is cut by the Mahanadi, Godavari, Krishna and Cauvery.
(c) The Plateau of Yunnan : This plateau covers part of South China, Thailand, Myanmar, Laos and Vietnam. This is also broken up by rivers such as the Salween, the Mekong and the Sikiang.
(iv) The Great River Valleys : These valleys are the areas of fertile soils and have abundant water supply. Most of these large rivers originate in the Central Mountain Belt and they are perennial. Important river valleys are :
(a) The valley of Euphrates and Tigris is an outlet through the Persian Gulf.
(b) The Indo-Gangetic plain covers the parts of Pakistan, India and Bangladesh. The Indus along with its five tributaries Jhelum, Chenab, Ravi, Beas and Sutlej, and the Ganga, the Brahmaputra and their tributaries drain this lowland.
(c) The Hwang-Ho, the Yangti Sikiang and the Sikiang basins lie in China.
(d) The Irrawaddy river in Myanmar, the Menam and the Mekong rivers in Indo-China are also river valleys. These rivers provide irrigation, power generation and navigation.
(v) The Island Groups : There are several islands of the eastern and the south-eastern coasts of Asia. Most of them are in the Pacific Ocean and form part of ‘Ring of Fire’. Japan, Philippines and Indonesia are a group of islands.
Factors affecting the Climate of Asia
Several factors affect the climate of Asia.
(i) Vast latitudinal and longitudinal extents : Asia’s vast east to west extent keeps a large part of the interior away from the influence of the sea. This gives a high yearly range of temperature over much of Asia. Due to large extent of the latitudes, a variety in climate from hot, wet equatorial type to cold, dry polar type is found.
(ii) Impact of distance from Equator, Distance from the Sea and Height above mean sea level on the Climate of Asia : Equatorial areas are hot and wet because sun rays fall vertically on this region throughout the year. The high temperature causes heating and vertical ascent of air by convection. A low pressure attracts winds from oceans. This is responsible for rainfall. Areas away from equator are deprived of this humid climate. Distance from sea makes the climate continental known for its extreme heat in summer and extreme cold in winter. The height above the sea level causes rainfall as high mountains acts as barriers for the motion of winds.
(iii) Impact of direction of Winds on the Climate of Asia : Wind blows from high pressure to low pressure and carries the weather conditions of the area over which it blows. Winds running over water bodies become humid and winds blowing over land are dry and hot. The direction of winds affect the climate of Asia. In winter, the whole of the Central and Northern Asia is occupied by a mass of cold, heavy air forming an area of high pressure. The dry winds now blow from land to sea. These give very little rain in the cold season. During the summer season, interior of Asia becomes very hot. As the air is heated, it expands and becomes light and a low pressure area is developed. It draws the air from the nearby cooler oceans which brings rain to most parts of Asia. Thus, change in the direction of winds affects the climate of Asia.
Conditions of Climate in Asia during the Summer and the Winter Season : In the summer season the interior of Asia becomes very hot. As the air becomes hot, it becomes light and a low pressure area develops in the region. Winds from the Indian Ocean blow towards this low pressure. These are summer monsoon winds. In south-east Asia and South China, winds from ocean to land blow. The coastal regions and slopes of mountain regions get high rainfall.
In the winter season, land cools more quickly than the surrounding ocean. Eastern Siberia has a temperature of–250C. High pressure occurs in Central Asia and Siberia. Cold dry winds blow from the interior of Asia towards the surrounding oceans. The cold dry winds blowing from the land do not give much rainfall. On eastern coasts in some areas, rainfall is received because winds blow from sea to land.
Climate and Vegetation Belts
(i) Equatorial : In some countries of Asia, like Indonesia and Malaysia, the climate remains hot and wet throughout the year. Here annual rainfall is above 300 cm by which tropical rain forests are found with tall trees and thick canopies. Their is dense undergrowth of shrubs and creepers. The rich wildlife of these forests includes apes, elephants, monkeys, sloths, tree lizards, tree, frogs, tapirs, birds and insects, etc.
(ii) Tropical Monsoon : Tropical monsoon climate is found in India and south-eastern Asia. Here summers are hot and winters are cool. Rainy season comes due to summer monsoon winds. Rainfall ranges from 50 cm to over 200 cm annually. The natural vegetation has deciduous trees due to marked dry period. The areas have tropical monsoon forests. Teak, sal, rose wood, deodar and bamboo are highly useful trees which are in abundance. Lions, monkeys, leopards, rhinoceroses, snakes, tigers and crocodiles are found here.
(iii) Tropical Desert : The desert in Saudi Arabia and the Thar Desert in India and Pakistan are the tropical deserts of Asia. In these deserts winters are cool and summers are hot. They are least affected by the monsoon. So, they receive little rainfall. During the day time the temperature is high. The scanty vegetation includes cacti, thorny scrubs and bushes. These deserts have animals like camels, scorpions, lizards, insects, gazelles, mules and horses.
(iv) The Mediterranean : The mediterranean climate exist in Turkey and other countries like Syria, Lebanon, Israel. Here summers are hot and dry and winters are mild and wet. The natural vegetation consists of evergreen shrubs and trees. Cedar, Oak and Olive are the evergreen trees. Wildlife has become scanty here because natural vegetation has been removed for agriculture and human settlements.
(v) Steppe : In central and western Asia, winters are very cold and summers are hot. Rainfall ranges between 25 cm and 50 cm, which is not sufficient for trees to grow. These plains are covered with short grass known as the steppe. These areas have very few trees. Here antelopes, wild horses, gazelles and camels, etc. can be seen.
(vi) Temperate Desert : Temperate deserts exist in the high plateau regions of Central Asia. They include the Gobi and Takta Makan deserts. Here summers are hot and winters are freezing. They have very low rain fall because of long distance from the oceans and the high mountain barriers. The land is barren and windswept. Vegetation consists of thorny bushes and short grasses. Animals like rodents, lizards and small insects can be seen here.
(vii) Warm Temperate : This climate is also called China climate and is found in central and eastern China, southern Japan and Korea. In this climate summers are hot and winters are mild. These areas have moderate rainfall ranging from 50 cm to 150 cm. Most rains are in summer due to the south-east monsoons. High temperature and heavy rainfall make evergreen trees to grow. Oak, camphor, magnolia and camelia are found here. Bamboos, lianas, ferns and palms grow in plenty. Large population has made wild life almost nil.
(viii) The Manchurian Type or the Cool Temperate : The Manchurian type climate is found in eastern coastal region of Asia, south of the Taiga particularly in north-east China in the plains of Manchuria and Hokkaido, the northern island of Japan. In this climate summers are short and warm while the winters are cold. Rainfall is moderate. These areas have coniferous trees like larch, spruce, pine and fir and deciduous trees like oak, beech, maple and birch. Animals with fur such as bears, foxes and squirrels are found here.
(ix) The Taiga : This region covers most of northern Russia and Siberia. In this region the annual rain varies between 25 cm and 50 cm and is mostly in the form of snow. Summers are cool, winters are very cold. Pine, fir, spruce and cedar are found here in abundance. These trees are used in making pulp and paper. Animals with fur like the lynx, mink, sable and squirrel exist here in large number.
(x) The Tundra : The northern part of Asia remains frozen for a major part of the year. Rainfall is mostly in the form of snow and scanty. The main vegetation consists of mosses and lichens. Polar bears, reindeers, arctic foxes, wolves and some birds are found in this region in summer but they migrate in winter.
