UPSC ONLINE ACADEMY

Geography & EVS

Red Panda

The red panda is endemic to the temperate forests of the Himalayas, and ranges from the foothills of western Nepal to China in the east. Its easternmost limit is the Qinling Mountains of the Shaanxi Province in China. Its range includes southern Tibet, Sikkim andAssam in India, Bhutan, the northern mountains of Burma, and in southwestern China, in the Hengduan Mountains of Sichuan and the Gongshan Mountains in Yunnan. It may also live in southwest Tibet and northern Arunachal Pradesh, but this has not been documented. Locations with the highest density of red pandas include an area in the Himalayas that has been proposed as having been a refuge for a variety of endemic species in the Pleistocene. The distribution range of the red panda should be considered disjunct, rather than continuous. A disjunct population inhabits the Meghalaya Plateau of northeastern India.

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Coral bleaching

Coral bleaching is the loss of intracellular endosymbionts (Symbiodinium, also known as zooxanthellae) through either expulsion or loss of algal pigmentation.The corals that form the structure of the great reef ecosystems of tropical seas depend upon a symbiotic relationship with algae-like unicellular flagellate protozoa that are photosynthetic and live within their tissues. Zooxanthellae give coral its coloration, with the specific color depending on the particular clade. Under stress, corals may expel their zooxanthellae, which leads to a lighter or completely white appearance, hence the term “bleached”

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HOT DESERTS

Hot deserts are located between 20°30° latitude in both the hemisphere on the western coast of the continents. They are also called Tropical Deserts. They are different from the mid latitude deserts and cold deserts, hot deserts are found in High pressure belts along the Tropics in the trade winds region. Distribution Of Hot Deserts: (i)Asia Thar desert and the Arabian Desert; (ii)Africa The Sahara and the Kalahari; (iii)N. America Lower California and Arizona states of USA; (iv)S. AmericaAtacama desert; (v)Australia The Great Australian desert. The Sahara desert of Africa is the biggest hot desert of the world. The Hot desert regions are located in the subtropical high pressure belts, which are not favourable regions for rainfall

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Clean Development Mechanism (CDM)

The Clean Development Mechanism (CDM) is one of the flexibility mechanisms defined in the Kyoto Protocol (IPCC, 2007) that provides for emissions reduction projects which generate Certified Emission Reduction units which may be traded in emissions trading schemes.The CDM is defined in Article 12 of the Protocol, and is intended to meet two objectives: (1) to assist parties not included in Annex I in achieving sustainable development and in contributing to the ultimate objective of the United Nations Framework Convention on Climate Change (UNFCCC), which is to prevent dangerous climate change; and (2) to assist parties included in Annex I in achieving compliance with their quantified emission limitation and reduction commitments (greenhouse gas (GHG) emission caps). “Annex I” parties are those countries that are listed in Annex I of the treaty, and are the industrialized countries. Non-Annex I parties are developing countries.

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Insolation & Heat Budget

Insolation : Insolation (from Latin insolare, to expose to the sun)[1][2] is the total amount of solar radiation energy received on a given surface area during a given time. It is also called solar irradiation and expressed as “hourly irradiation” if recorded during an hour or “daily irradiation” if recorded during a day. Absorption & Reflection : The object or surface that solar radiation strikes may be a planet, a terrestrial object inside the atmosphere of a planet, or an object exposed to solar rays outside of an atmosphere, such as spacecraft. Some of the radiation will be absorbed and the remainder reflected. Usually the absorbed solar radiation is converted to thermal energy, causing an increase in the object’s temperature. Manmade or natural systems, however, may convert a portion of the absorbed radiation into another form, as in the case of photovoltaic cells or plants. The proportion of radiation reflected or absorbed depends on the object’s reflectivity or albedo. Direct insolation is the solar irradiance measured at a given location on Earth with a surface element perpendicular to the Sun’s rays, excluding diffuse insolation (the solar radiation that is scattered or reflected by atmospheric components in the sky). Direct insolation is equal to the solar constant minus the atmospheric losses due to absorption andscattering. While the solar constant varies with theEarth-Sun distance and solar cycles, the losses depend on the time of day (length of light’s path through the atmosphere depending on theSolar elevation angle), cloud cover, moisture content, and other impurities. Insolation is a fundamental abiotic factor[4] affecting the metabolism of plants and the behavior of animals. Heat Budget : The Earth and the atmosphere are heated by energy from the sun. Theatmospheric heat budget of the Earth depends on the balance between insolation and out going terrestrial radiation. This budget has remained constant over the last few thousand years. The amount of energy received from the sun is determined by;• The solar constant – varies slightly and affects longer term climate rather than short term weather variations.• The distance from the sun – the eccentric orbit of the Earth can cause a variation of up to 6% in the solar constant.• The altitude of the sun in the sky – the equator receives more energy as solar radiation strikes the Earth head on, whereas at 60 N or 60 S the angle creates twice the area to cover and increases the amount of atmosphere to go through.• The length of day and night –The Earth receives energy from the sun as insolation. Some is lost as it passes through the atmosphere but overall the surface has a net gain of energy, the exception being the polar regions. Only about 24% of this insolation reaches the surface as it is either absorb, reflected or scatteredThe atmosphere in contrast has a net deficit of energy. Because of this difference, heat is transferred from the surface to the atmosphere by radiation, conduction and by the release of latent heatHeat budget by latitudeThere are variations in energy and heat between latitudes. Low latitudes have a net surplus of energy, mainly because of their relative proximity to the sun. The high latitudes (pole wards of 40 N and 40 S) have a net deficit. As the tropics are not heating up and the poles are not cooling down, a transfer of heat must occur.This occurs by:• Horizontal heat transfers: air movement (winds, 80%, including the jet streams, hurricanes and depressions) and water movement (ocean currents).• Vertical heat transfers: energy is transferred from the warm surface vertically by radiation, conduction and convection. Latent heat also helps to transfer energy, e,g, when water is evaporated. This energy is released when condensation occurs in the upper atmosphere

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Composition of Atmosphere

Composition of Atmosphere : The atmosphere is mixture (composition) of many types of gases. It consists of 73% nitrogen, 21% oxygen and argon 0.9%. Other gases like carbon dioxide, hydrogen, helium and ozone are present in minute (small) quantities in the atmosphere. The lower layer of the atmosphere contains water vapor. This water is added to the lower layer of atmosphere from oceans, lakes and other water bodies by ways of evaporation. It is hardly 3-4% but it plays an important role in the atmosphere processes. Besides this, the lower layers of the atmosphere also contain dust, salt, pollen grains, etc.

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Structure of Atmosphere

Structure of Atmosphere: TroposphereThe lowest layer of the structure of atmosphere is called troposphere. The upper limit of the troposphere is called the tropopause.The troposphere is most dense and extends up to a height of 18 km along the equator and about 8 km. along the poles.In this layer, the temperature of air decreases with height at an average rate of 1°C for every 165 meters.StratosphereThere is another layer above the Troposphere which is called Stratosphere. The thickness of stratosphere is 40-50 km.In this layer temperature remains constant and then decreases with height. This layer is free from clouds. The conditions in this layer are ideal good for flying of Jet aircraft. The ozone in this layer absorbs harmful ultra-violet radiation from the sun.MesosphereThe mesosphere extends above the stratosphere. It is a 30 km deep layer.ThermosphereThis is the fourth layer of the atmosphere this layer extends from 80 km to the top layer. Its lower part is called ionosphere. Ionosphere contains ions. These particles reflect radio waves to the earth’s surface and enable wireless communication.The upper part of thermosphere is called exosphere. Exosphere starts 500 km above earth. There is no distinct upper limit to the exosphere and this gives way to interplanetary space.The whole atmosphere envelop weighs about 5000 million tons. The weight exerts a constant pressure of about 1 ton on the human body.BiosphereIt means sphere of life. The idea of biosphere was given to us about a century ago by the Australian geologist. The distinguishing feature of the biosphere is that it supports life. It is estimated that the biosphere contains more than 3,50,000 species of plants including algae, fungi, moss and higher forms of plants and eleven million animal species ranging from unicellular protozoa to man.The biosphere supplies the essential requisites life for all these species, namely light, heat, food and living space or habitats. The biosphere and ecosystem is one and the same thing. The eco-system depend upon a whole set of delicately balanced cycles. These cycles are energy cycle, heat cycle, carbon cycle, oxygen cycle, nitrogen cycle and water cycle.

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Factors affecting rate of Weathering

Factors affecting rate of Weathering : 1. MineralogySome minerals are more susceptible to weathering. The dark minerals are also more affected by thermal weathering than light coloured ones. A rock that is polymineralic is more subject to destruction than one that is monomineralic. This is because coefficients of linear expansion and therefore undergo different deformations with variations in temperature with protracted temperature variations, mutual cohesion between individual grains is disrupted and the rock disintegrated.2. TextureIn principle, the finer grained rock is the greater the surface area exposed and hence the greater the surface area are exposed and hence the greater intensity of weathering.However, if a rock has coarse grains that are easily weathered, the great holes left may weaken the rock rapidly and therefore enhance the rate of weathering.3. DiscontinuitiesThese provide surfaces along which weathering can take place easily (i.e. where agents of chemical weathering can penetrate and act). They include joints, faults, bedding planes and cleavage. The fractures are gradually widened by weathering until the rock is completely split into parts.4. ClimateRegions with large diurnal range (daily temperatures variations) undergo the most intensive thermal weathering.This is most pronounced in deserts. Importance of weathering: 1. Leads to the breakdown of rocks into smaller particles until soil is formed which is valuable agricultural uses2. Weathered land forms are tourist attractions.3. Weathered land forms are used for research purposes.4. Weathering products transported to the sea by rivers as dissolved solids make sea water salty and serve as nutrients for many marine organisms.5. Some metallic ores, such as those of copper and aluminum, are concentrated into economic deposits by chemical weathering.  

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Agents Of Erosion

Agents of erosionThe erosion is caused mainly by the three agents:-i) Waterii) Windiii) IceThe fourth agent which helps is gravity.WaterWater is the most important agent of erosion responsible for the maximum havoc it creates in the form of erosional damages to the land surface.It may act in three forms i.e. as falling drops, running overland flow and as running rivers and streams. The erosion caused by water is generally quite devastating and may create various engineering problems, if not properly checked or accounted for, while planning the engineering projects. WindThe earth, as you know is surrounded by an environment of gases, called the atmosphere. The movement of the atmosphere in a direction parallel to the Earth’s surface, is wind, where as the vertical movements of the atmosphere are termed as air- currents. The cause of wind formation is the subject of a science called Meteorology, and is beyond the scope of this program. We under engineering Geology are mainly concerned with the geological work done by wind, in the form of erosion and consequent deposition of the eroded material.Like water, wind is also an agent of erosion, transportation, as well as deposition. It is quite an effective agent of erosion in deserts and arid dry areas. Erosion by moving iceA glacier is a mass of moving ice, which causes erosional of the surface over which it moves. The third agent of erosion i.e. ice or glaciers may also cause a lot of erosional damages, although it becomes slightly less important in a tropical country like Uganda. The eroded material is carried in an embedded state by the glacier over some distance and then deposited at some place(s) as and when the sediment load gets separated out due to over-loading or sudden disturbance or melting of glacier itself. A glacier, like water and wind, thus act as an agent of erosion, transportation, as well as deposition. About 10% of our present land of the globe is covered by glaciers. They are slow erosive agents, much less effective than water, as far as the overall erosion is concerned. However, in areas of excessive snow falls, such as in mountain tops and solar regions, they become quite effective over a period of time and are thus believed to have developed many land forms (i.e. geological features) of the world

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Weathering-Introduction & its types

INTRODUCTION: The rock surface of the continents of the Earth, on which we are living, is undergoing constant and continuous destruction, a process called denudation.Denudation is the process by which the land areas are continually being reduced and their shape modified by weathering and erosion.Rocks exposed at Earth’s surface are constantly being altered by water, air, changing temperature and other environmental factors. The term weathering refers to the group of destructive processes that change the physical and chemical character of rock at or near Earth’s surface. The tightly bound crystals of any rock can be loosened and altered to new minerals by weathering.It is important to distinguish between weathering and erosion and between erosion and transportation. Weathering breaks down rocks that are either stationary or moving. Erosion is the picking up or physical removal of rock particles by an agent such as streams or glaciers. Weathering helps break down a solid rock into loose particles that are easily eroded.Most eroded rock particles are at least partially weathered, but rock can be eroded before it has weathered at all. A stream can erode weathered or un-weathered rock fragments.After a rock fragment is picked up (eroded), it is transported. Transportation is the movement of eroded particles by agents such as rivers, waves, glaciers, or wind. Weathering processes continue during transportation.A boulder being transported by a stream can be physically worn down and chemically altered as it is carried along by the water. Types of weathering: These are three types of weathering namely:-i) Mechanical weathering or disintegration.ii) Chemical weathering or decompositioniii) Biological weathering. Mechanical weathering or disintegrationThis is the breakdown of rocks into small particles by the action of temperature, by impact from rain drops and by the abrasion from mineral particles carried in the wind. Products of mechanical weatheringThe products of mechanical weathering include everything from huge boulders found beneath the cliffs to the smallest silt. Processes most commonly involved in mechanical weathering.1. Mechanical unloadingThis is the vertical expansion due to the reduction of vertical load by erosion.This will open existing fractures and may permit the creation of new fractures.2. Mechanical loadingThis is impact on rock and abrasion, by sand and silt size. Wind borne particles that occur in deserts, impact on soil and weak rocks, by raindrops during intense rainfall storms.3. Thermal loading.This is expansion by freezing water in pores and fractures in cold regions or by the heating of rocks in hot regions.4. Welting and drying.Expansion and contraction associated with the repeated absorption and loss of water molecules from mineral surfaces and structures.5. Crystallization.This is expansion of pores and fissures by crystallization within them, of minerals that were originally in solution.Note: Expansion is only severe when crystallization occurs within a confined place.6. Pneumatic loading.The repeated loading by waving of air trapped at the head of fractures exposed in the wave zones of a sea cliff.Chemical weatheringThis is the breakdown of minerals into new compounds by the action of chemical agents; such as acid in the air, in rain and in river water; although they act slowly, produce noticeable effects especially in soluble rocks. The rate of chemical weathering depends on temperature, the surface area and the amount of water. Chemical weathering causes the old minerals to disintegrate and to form new minerals. Minerals which are originally formed at lower temperatures in the original igneous rocks during the process of cooling of magma prove more resistant to chemical weathering compared to those which were formed at high temperatures during the cooling of Magma.Processes of chemical weatheringProcesses are most commonly involved in chemical weathering are listed below and their rate of operation depends upon the presence of water and is greater in wet climates than in dry climates. Some commonly occurring processes in chemical weathering are: 1. Solution.This is dissociation of minerals into ions greatly aided by the presence of carbon dioxide (CO2) in the soil profile, which forms carbonic acid (H2Co3) with percolating rain water.2. OxidationThis is the combination of oxygen (O2) with a mineral to form oxides and hydroxides or any other reaction in which the oxidation number of the oxidized elements is increased.3. Reduction.The release of oxygen (O2) from a mineral to its surrounding environment; ions leave the mineral structure as the oxidation number of the reduced element is decreased.4. Hydration.This is the absorption of water molecules into the mineral structure.Note: This normally results in expansion; some clay expands as much as 60% and by admitting water hastens the process of solution, oxidation reduction and hydrolysis.5. HydrolysisHydrolysis is the reaction with water. Hydrogen ions in percolating water replace mineral cations; no oxidation reduction occurs. In other words, hydrolysis is a chemical reaction in which a compound reacts with water causing decomposition and the production of two or more other compounds. 6. LeachingThis is the migration of ions produced by the above processes.Leach. (To drain away from soil when dissolved in rain water, lose a mineral or chemical dissolved in rain water.Note: The mobility of irons depends upon their ionic potential. Calcium (Ca),Magnesium (Mg), Sodium (Na), and Potassium (K) are easily leached by moving sodium water, Iron (Fe) is more resistant, Silicon (Si) is difficult to leach and Aluminum (Al) is almost immobile.7. Cation exchange.This is the absorption onto the surface of negatively clay of positively charged cations in solution especially Calcium (Ca), Hydrogen (H), Potassium (K), and Magnesium (Mg).Biological WeatheringThis describes those mechanical and chemical changes of the ground that are directly associated with their activities of animals and plants. When present, microbial activities can change the chemistry of the ground close to ground level.

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