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Natural Resources, , , , Atmosphere : It is the multi-layered gaseous envelope surrounding the earth., , , , Layers of atmosphere : Troposphere, stratosphere, mesosphere, thermosphere (or, ionosphere) and exosphere, , , , Role of the atmosphere, , o, o, , It acts like a blanket, thus covering the earth., It absorbs heat from sunlight, thus keeping the average temperature of the earth steady., , , , Wind – It is caused by the uneven distribution of heat over the Earth’s surface., , , , Formation of Wind, , o, o, o, , Wind is formed as a result of the differential heating of the atmosphere., During the day, wind blows from sea to land. This is known as sea breeze., During the night, wind blows from land to sea. This is known as land breeze., , , , Factors governing movement of air, , o, o, o, o, o, , Wind is formed as a result of the differential heating of the atmosphere., Rotation of the Earth, Relief features of the Earth, Vapourisation and condensation, Uneven heating of land in different regions of the Earth, , , , Sources of water: The common sources of water are ponds, lakes, rivers, wells, and, reservoirs., , , , Water cycle: Water undergoes different processes in the environment and is found in, different states during these processes. This cyclic process through which water circulates, in the environment is called the water cycle., , , , Importance of water, , o, , Water is necessary for germination of seeds, transportation of nutrients from soil and food, from the leaves to different parts of the plant, in preparation of food through, photosynthesis., , o, , Aquatic animals and plants get their nutrients as well as oxygen supply from the water., These substances are present in water in dissolved form.

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o, , Water is used for many other purposes such as in cooking, cleaning, industrial work,, running hydroelectric and thermal electric power plants. Sea water is also used as a, medium of transportation., , , , A solution has two components, namely the solvent and the solute., , , , Solvent is that part of the solution in which the other component is dissolved. In other, words, solvent is that component of a mixture that is present in large amounts., , , , Solute is that part of the solution that is dissolved in the solution. This is present in a lesser, quantity as compared to the solvent. Also, more than one solute can be present in a, solution., , , , Properties of a solution, , o, o, , It is a homogeneous mixture of solutes and solvents, The solute particles in a solution are extremely small in size. They are less than 1 nm (109 m) in diameter., Solute particles are not visible to the naked eye., As a result of the small size of the solute particles, a solution does not scatter light., Solute particles being small in size get dissolved in the solvent. Hence, the solute cannot be, separated from the solution by filtration., Solute particles do not settle down when left undisturbed., The addition of harmful substances to water which causes its physical, chemical and, biological properties to change is called water pollution., , o, o, o, o, o, , , , Uses of Water, Water is used for many purposes like drinking, washing clothes and utensils, generating, electricity, bathing, irrigation etc., , , , Soil is the layer of earth that results from the degradation of the basement rock— also, known as bedrock—due to certain physical, chemical and biological processes. The quality, of a soil is influenced by the microscopic organisms found in it.

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, , Components of soil:, , o, o, o, o, , Small particles of rock, Humus, Microscopic life, Nutrients, , , , Factors influencing formation of soil:, , , , Importance of soil:, , , , Soil Erosion - The removal of the top layer of soil, , , , Soil Pollution - The introduction of the substances like toxic compounds, chemicals, salts,, radioactive materials in the soil, , , , Prevention of soil erosion:, , o, o, o, o, o, o, , Parent material, Climate, Topography, Organisms, Time, Afforestation

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o, o, o, , o, o, , Terrace farming, Proper irrigation techniques, Construction of proper embankments, Air pollution, A change in the quality of air brought about by the addition of harmful substances, either, by humans or by environmental processes, is termed as air pollution., The important sources of air pollution are burning of fossil fuels, burning of wood;, automobile exhaust, combustion, refrigerants such as Freon, aerosol sprays etc., , , , Water Pollution, , o, , o, , A change in the quality of water brought about by the addition of harmful substances by, humans is termed as water pollution., Important factors that pollute water are fertilisers and insecticides, sewage from towns and, cities, waste from factories/industries., A change in the temperature of water is also a form of pollution., , , , Greenhouse effect, , o, o, , Trapping of heat by gases (CO2) in the atmosphere., Gases that cause the greenhouse effect are responsible for increasing the temperature of, the Earth and thus contributing to the phenomenon called global warming., , , , Causes of Green house effect, , o, o, , A part of solar radiations cause warming of the earth’s surface., A part of solar radiation is reflected back, which is trapped by the earth’s atmosphere. This, phenomenon is called green house effect., , , , Green house gases, , o, o, , These are the gases, which trap the solar radiations, and in this way, are responsible for the, increase in the temperature of Earth., The examples include carbon dioxide, methane, nitrous oxide, and water vapours., , , , Global warming, , o, , The CO2 level in atmosphere is increasing due to various human activities such as, deforestation and burning of fossil fuels., Build up of CO2 in the atmosphere will result in a rise in the average temperature of earth’s, atmosphere, leading to global warming., Global warming will lead to melting of glaciers and increase in the sea level., , o, , o, o

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, , Ozone layer, , o, o, , Ozone (O3) is a form of oxygen and is more stable than the two-atom oxygen (O2)., The ozone layer protects and prevents these ultraviolet radiations from reaching the, Earth’s surface., The pollutants that are responsible for depleting the ozone layer are gases such as chlorine, and fluorine., As a result of ozone depletion, a hole has developed in the ozone layer over Antarctica and, its size has been steadily increasing over the years., , o, o, , , , Water Cycle, , , , Carbon cycle, , , , Oxygen cycle