Geography notes for competitive exams

 

TYPES OF CLIMATES:

Koeppen divided the world climate into five major groups each designated by a letter code.

(a) Tropical Climate
(b) Dry Climate
(c) Humid Mesothermal Climate
(d) Humid Microthermal Climate
(e) Polar Climate

Koeppan also identified a sixth type that is Mountain or highland climate.

(a) Tropical Climate: This climate occurs in the tropical zone, where the mean monthly temperature remains generally above 22° C. They do not have a perceptible winter season. The major subtypes of this climate are the Tropical rainforest, tropical monsoon and tropical savanna climates. Tropical Rainforest is characterized by year round precipitation and the areas support dense ever green forests of tall trees. The basis of the dense and tall forests is the high temperature and a large amount of precipitation, generally over 250 cm. The average temperature in this region is 27° C. The climate of the equatorial regions such as Indonesia, the Congo Basin and Amazonia is of this type. In the Tropical Monsoon, the rainfall is seasonal and generally occurs in summer and may be as high as 300 cm in favourable locations. Due to this, the vegetations in these regions is of deciduous type that is the trees shed their leaves during the dry season. The average temperature in this region is 26° C. India, China and her neighbours in South East Asia constitute a major area of this type of climate. In the Tropical Savanna, the total amount of rainfall is lesser, about 160 cm. Annual average temperature is about 23°C. Due to lack of rainfall, the typical type of vegetation in these regions is the open thorn type of forests and grasslands with occasional clumps of trees. Savanna type of climate is transitional between the tropical wet climate towards the equator and the dry climates towards the poles. Parts of Northern Australia, the Veld region of Africa and Venezuela are the areas of this type.

(b) Dry Climate: This climate is characterized by a general water deficit. The annual precipitation is less than the potential evaporation and no permanent streams originate from such regions. It has two major subtypes – tropical and subtropical deserts and the tropical and subtropical steppes. The Tropical and Subtropical Deserts have temperature of about 38°C with an annual range of about 25°C. The average rainfall is about 25 to 40 cm. The typical areas of this type are the Sahara, Atacama, the Thar, Gobi, Arabian and the Kalahari desert. This type of climate covers a vast area of Australia also. Most of the tropical deserts occupy the western margins of the continents near the tropics. The subtropical deserts are usually in the interiors of the continents where the moisture bearing winds fail to reach. Due to lack of rainfall, the deserts have very limited plant and animal life. The tropical deserts are also called hot deserts. The Steppes are areas of comparatively lower temperature and slightly more precipitation. Annual average temperature is about 21°C. Rainfall is not only limited. It is also highly variable. Temperature grasses are the chief vegetations of these regions. They occupy pole ward margins of the tropical and subtropical deserts. Much of the precipitation in these regions is provided by the cyclonic storms. North American Prairies, South American Pampas, South Africa Velds,Hungary Postas, Australia Downs, New Zealand Canterbury and Eurasian Steppes are the major areas of these grasslands. These regions are ideally suitable for the cultivation of grain crops such as wheat.

(3) Humid Meso thermal Climate: This type of climate is subdivided into three types Mediterranean, China and west European type. Mediterranean Type of climate is typical of the western coastal parts between 30° and 45° latitudes in both the hemispheres. The annual average temperature is 16°C with a summer average of about 25°C and a winter average of 10°C. Annual rainfall is 40 to 60 cm and occurs in winter and summers are dry. Olives, grapevine and citrus fruits are the chief products of this region. Mediterranean Sea, Central region of Sea, Southern tip of South Africa and South western part of Australia are the regions of this type of climate. The China type of climate is characterized by warm summers and cool winters, the average temperature is being around 19°C and annual rainfall about 120 cm. This type is experienced in the eastern region of the continents in the same latitudes in which the Mediterranean type of climate is found. Rainfall is available throughout the year. The major areas are China, Argentina, South eastern Part of USA and eastern coastal region of Australia. The typical areas of the West European type of climate are the coastal region of Western Europe. This region extends between the latitudes 40° and 60° N and S and includes Western Europe,parts of North America, South America and South eastern coastal region of Australia. The summers are cool but winter is cold and temperature goes below 10°C. Rainfall occurs throughout the year but it is heavier in the winter season.

(4) Humid Micro thermal Climate: This type of climate is experienced in two large belts one each in North America and Eurasia. Based on the type of forests growing there, this climate is also known as TAIGA. Most of the Siberian region and high latitudes of USA and Canada have this climate, which have cool summers and cold winters. Total annual precipitation is generally below 50 cm, but on account of the low temperatures this is enough to support the Coniferous forests. Fur farming is very famous now a days in these region.

(5) Polar Climate: This climate is also known as the TUNDRA type of climate and it experienced in the polar regions. This is characterized by severe winters and even the summers are cold. The precipitation is very low, generally below 30 cm. Due to low temperature, vegetation is practically non-existent. Only during the short summer season do some small plants grow in the areas away from the polar ice caps. These regions are known for BLIZZARDS, which are high velocity winds carrying ice particles with them. These regions are called cold deserts and they occupy the areas of the Arctic margins of North America and Eurasia and Antarctic continent. Vegetation is Lichens and Mosses.

(6) The Highlands Climate: This type of climate is experienced in the mountain regions of the Himalaya, Tibetan Plateau, Rockies, Andes and the Alps.

HYDRO Logical Cycle and Global water balance.

Water occurs in three major pools, namely in the form of ground water in the rocks of Earth, as surface water in rivers,lakes, seas, oceans or as ice in the polar and high altitude regions and as vapour in the atmosphere. These three pools of water are interconnected and the water keeps moving continuously from one pool to the other. This is called Hydrological cycle. The largest reservoir of free water is in the oceans and nearly 455,000 cubic km of water evaporates from the oceans annually. Another about 62,000 cubic km of water evaporates from the continents. The quantity of water added to the atmosphere and returned to the Earth in the form of precipitation, is equal. This is called the Global Water Balance. However the distribution of precipitation is uneven. While more water is added to the atmosphere from the oceans, more of the precipitation occurs on land. This excess quantity of water available on land flows into the water bodies either as surface run off or as sub surface flow. Thus an overall balance is maintained in the amount of water lost from the Earth and returned to it. On an average, oceans account for 97.2% of total water available on the Earth, the atmosphere contains only about 0.001% and the ice caps and glaciers account for about 2.15 %. The ice caps are thus the largest reservoirs of fresh water.
Out of the total amount of rainfall, apart is absorbed by the soil in the form of Soil Water. The remaining water flows over the surface as Surface Run Off. When the soil gets saturated, the water starts moving downwards through the rocks. The process of water entering the rocks of the Earth is called Percolation. The rate of percolation is a function of the porosity and permeability of the rocks. Porosity refers to the presence of pores in the rocks while permeability refers to the capacity of the rocks to allow water to move from the upper to the lower parts. The water percolating and thus occurring in the rocks of the Earth is called the Ground Water. Some water may be present in the rocks of the Earth right from the time of their formation. Such water is called connate water. That zone of rocks in which the pore space is completely filled by water is called the Zone of Saturation. The upper most surface of this zone of Saturation is called the Water table. The rocks of the Earth that contain water are called Aquifers. Some of the Earth are non porous and they do not contain any water. Such rocks are called Aquicludes.

Spring Water: Spring is formed where the water table intersects the ground. Sometimes the water flows out of the ground in a very small quantity from the saturated rocks. This type of limited flow is called Seepage. Springs may be seasonal or perennial. In some of the springs emerging water is hot and they called as hot springs due to certain minerals in the rocks, which upon reaction with water produce heat. Some springs have medicinal properties due to some minerals. A large number of springs occur in Kumaon Himalayas in Uttara Khand and in Himachal Pradesh.

Geysers: A geyser is a periodic jet of hot water and steam. The source of geyser is very deep and the water at the depth is heated by the surrounding hot rocks. The water changes into super heated steam and a jet of water is thrown out followed by steam escaping with a hissing noise. Some of the water again flows into the opening and the whole process is repeated at a regular interval. The most well known in the geysers is Old Faithfull in the Yellowstone National Park in USA which erupts every 65 minutes. Japan, Malayan Archipelago, New Zealand and Alaska also have many geysers.

Artesian Wells: In artesian wells the water rises to the surface on its own and no power is needed to draw water from it. The areas where the artesian wells can be dug are called artesian basins. The artesian basin of Australia is well known area for artesian wells.

HYDROSPHERE

•  It is most important sphere of Earth and covers 71% of Earth’s surface and its average depth is 4 km.
• Like surface, ocean floor is also very irregular.
•  Its depth is measured in fathom. 1 fathom = 1.8 m
•  The Pacific Ocean covering about 1/3rd of the total area of the Earth and is the largest and deepest ocean. Most of the Eastern coast of this ocean is smooth and only along the western coast, large indentations occupied by various marginal seas are found.
•  Continental Shelf: It is not so deep. It is the coastal part of the ocean and the slope of the bottom is very gentle and it is not more than 100 fathoms. 20% (approx.) petrol and gas is found here. In regions where the mountains extend along the coast is found narrow shelf. Marine life exists entirely here. In India the breadth of the Shelf is less along the Bay of Bengal coast than along the Arabian Sea coast.
•  Continental Slope: This is the outermost part of the true ocean basin and extends seawards from the continental shelf. The boundary between shelf and slope is called as Andesite Line. Its depth is up to 2000 fathoms.
•  Continental Rise: It is found at the foot of slope (convex slope) . It is the area slightly rising due to the accumulation of debris transported on the slope. Large number of oil deposits is found here.
•  Ridges: These are the mountains of the sea. Many shape of the ridge is found in the ocean (Mid Atlantic Ocean inverted Y shape and Indian Ocean Ridge is S shape). Some parts of the ridge or volcanic peaks reach the surface of the oceans and form Islands (Example Hawaii). The ridges rising more than 1000 m above the ocean floor is called Seamount. Those flat top seamounts are called Guyots maximum in pacific oceans.
•  Trenches: Trenches are deep and narrow areas of the ocean. Example, Marina Trench or challenger (deepest trench) 11022 m in the western Pacific near Japan. Others are Tuscarora Deep (Off Japan), Tonga Trench (Pacific Ocean, 11000 m), Comedic trench (Pacific Ocean, 10800 m), Java Trench (Indian Ocean, 7450 m), Poutorica Trench (Atlantic Ocean, 91217 m).
•  The mid oceanic ridges are associated with plate divergence where the oceanic crust gets fractured and the molten material rises to form ridges which push the older rocks towards the ocean margins. This phenomenon is called Sea Floor Spreading. The relatively raised board areas on the sea floor are called Platforms and the relatively lower bowled shaped areas are called Basins.
•  Indian Ocean Current

              1. South Equatorial Current (Warm)

              2. Equatorial Centre Current (Warm)

              3. Monsoon Current (Warm)

              4. Mozambique and Agulhas Current (Warm)

              5. West Australian Current (cold)

              6. South Indian Current (Cold)

         (The Monsoon current flows from the South West in July and from the North east in January.

•   Types of Coasts:

                1. Fjords: Fjord coasts are not good ports because they are formed as a result of partial submergence of a glaciated area. They have very steep sides. Example, Coast of Norway

                 2. Ria: Ria forms better ports than Fjords because they have gentle slope due to partial submergence of highland. Example Coast of south west Ireland.

                 3. Dalmation: Good for ports because of the submergence of mountain ridges which run parallel to the sea coast. Series of fold mountain range can be along the coast. Example, Yugoslavian Coast.

•  Major Canals:

Canals are man-made channels for water. There are two types of canal:

1. Waterways: navigable transportation canals used for carrying ships and boats shipping goods and conveying people, further subdivided into two kinds:

                 1. Those connected to existing lakes, rivers, or oceans. Included are inter-basin canals, such as the Suez Canal, Erie Canal, and the Panama Canal.

                 2. Those connected in a city network: such as the Canal Grande and others of Venice Italy and the waterways of Bangkok.

2. Aqueducts: water supply canals that are used for the conveyance and delivery of potable water for human consumption, municipal uses, and agriculture irrigation. Rills and acequias are small versions.

                 1. Suez Canal: Built in 1869 by the French engineer (Ferdenand de Lesseps) and was nationalized by Col- Nasser (Egypt) 26, July, 1956. Connected between Mediterranean Sea and Red Sea. 193 Km long, 24m deep and 205 m wide and is the Greatest Canal. Suez Canal also known as “Highway to India”.
                 2. Panama Canal: Connected Atlantic Ocean (via the Caribbean Sea) and Pacific Ocean. 58 km Long. Opened in 1914.

                  3. Kiel Canal: Connected London and Baltic Ports (North Sea and Baltic Sea). 98 Km long.

•  Major Water Transportation:

           1. North Atlantic Sea Route: Connected Eastern coast of North America and Western Europe. World’s Largest busy transport route.

           2. South Atlantic Sea Route: Connected South American countries and Western Europe.

           3. North Pacific Route: Connected North America and East Asia.

           4. South Pacific Route: Connected North America, Europe and Australia.

           5. Mediterranean Sea and Indian Ocean Route: Connected America, Europe, Asia and African  countries.
This route is famous for oil trade.

•  Earth Quakes:

                     Earth quake is a vibration of Earth Surface produced by internal forces and its passage of waves is recorded by seismograph. The point of origin of earth quake is called Seismic Centre or focus. Most of the earthquakes originate at a depth of about 60 Km below the surface of the Earth. The intensity of waves is measured by Richter’s Scale. The point on the earth’s surface vertically above the earth’s surface is called Epicenter. Types of waves are Primary, secondary and surface or long waves. Primary waves travel very fast. It transmitted through solids, liquid and gases. Travel from the point of happening by displacement of surrounding particles. Secondary waves travel through solid matter only so that it cannot pass through core of the Earth. Surface waves or Long
waves causes maximum destruction on Earth and it travels on Earth surface. According to Elastic Rebound Theory, the rocks of the Earth when pressed due to increasing overburden get pushed into the zone of high density in the interior. However the rocks have a tendency to resume their original position if the pressure over them is released. Whenever this type of movement of rocks occurs, an earthquake is caused.