The Environment - Class Note

THE ENVIRONMENT What is Environment ? The enviroment is defined as the cwhole physical and biological system encompassing man and other organisms survive and sustain. It surrounds us, it influences us. It controls growth and development of living organisins. It is comprised of interacting system of physical. chemical and biological and cultural elements which are interlinked with each other. It is nature's gift that help in nourishing life on earth. Environment is derived from the French word 'Environ' which means 'surroundings. Different segments of environment. a) Climatic Factors: Solar radiation, temperature, wind, water. current, rainfall. b) Physical Factors! Light, Air c) Clinical Factons Oxygen, carbon dioxide, acidity, salinity, availability or inorganic nutrients. Basic Components of Environment The Environment has Pour basic components 1) Atmosphere, 2) Hydrosphere, 3) Lithosphere and 4) Biosphere. There is continued interactions between abiotic abiotic abiotic biotic and biolic- biotic components. Atmosphere Biosphere Lithosphere Hydrosphere 1) Atmosphere The atmosphere is the blanket of air that adheres to the earth's surface. Atmosphere is a protective layer of gases that shelters all life on earth, keeping temparature within a relatively small range and blocking out harmful rays of sunlight. It is held near the surface of the planet by earth's gravitational altraction. It begins from a few metres within the soil or the water surface and extends to a height of about 60.000 km. above the earth.. Lagens of atmosphere:- The atmosphere has five distinct layens that are a) Troposphere b) Stratosphere c) Mesosphere d) Thermosphere e) Exosphere a) Troposphere. The troposphere is the first and lowest layer of the atmosphere of the earth and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerasals and is where most weather phenomena occur. It extends upward to about 10 kim. above sea-level starting from ground level. The lowest part of the troposphere is called the 'tropopause! Troposphere does not contain ozen. The troposphere is essential as it contains the earth's weather as well as greenhouse gases to maintain the temparature of earth. The cold layer at the top of troposphere which shows a temperature invertion that is negative to positive lapse rate is called 'tropopause'.. (b) Stratosphere:- Above the troposphere lies the stratosphere which extends from the top of the troposphere to about 50 kn above the ground. The lower layers of the stratosphere are cold and as we move upwards the upper layers become hotter. The ozone layers forms the upper crust of the stratosphere which is approximately. 90% of the ozore in the asmosphere. The layer combines oxygen atoms to Porm the ozone molecules. Ozone in molecules absorb harmful tutraviolate (UV) radiations from the sun. C) Mesosphere! The mesasphere is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature: decreases as altitude increases. It extends to a height of about 80 km from the ground. The coldest parts of mosphere ore located in this layer and can reach -90°C. Here the lapserate is negative against due to loco rate of ozone. (d) Thermosphere. + Thermosphere lies above the mesosphere and this is a region where the temperature increase as you go higher up. It extends to a height of about 60-700 km. The temperature increase is caused due to the absorpation of energetic ultraviolet and x-ray radiation from the sun. However, the air in the layer is so thin that. It would feel freezing cold to us. Temperature in the upper thermosphere can range from about 500°C to 2000°c or higher. The aurora, the Northen lights and southern lights. occur in the thermosphere. This layer protect our planet by absorbing harmful radiation. This layer is also known as 'Ionosphere'.. Prosphere Frasphere is the Anal Pontier of the earth's gaseous envelope. 14 externels to a height of 200-1000 km. The air in the exosphere gradually leaking out of the earthis atmosphere trito eder space. the exosphere is the very edge of nur atmosphere. This layer is mainly composed of extremely low density of hydrogen, helitum and several heavier molecules including nitrogen. The temperature of this layer varles dramatically. Hydrosphere. A hydrosphere is the total amount of water on a planet. 12 includes water that is on the surface of the planet, curderground and in the air. A planet's hydrosphere can be liquid, vapour or ice. 14 is vital for the life molecule to survive. Water possesses a number of physical and chemical properties that help the molecule to act as best suited medium for life activities. The oceans cover approximately 71% of the planet, glaciers and tee caps cover additional areas and water is also found in takes and stream, in soils and einderground reservoirs, in the atmosphere and in the bodies of all living organism. Thus water in all its forms. ire, liquid, water and water vapour is very familier to 05. 3) Lithosphere. The lithosphere is the rigid, outermast shell on earth. It is composed of the crust and the portion of the upper mantle lower mantle outer and inner core, the outermost shell of a rocky plant, the crust is defined on the basis of its chemistry and minerology. Basinally lithosphere is nothing but a artistal system composed of various. layers, Core, mantle and order crust Variocas elements constitute such crustal lager in mixture of different proportion. There are two types of crust. That are Continental crust the relatively thick part of the earth's crust which forms the large land masses, and Oceanic crust the outermost layer of earthis lithosphere found under oceans. The earth's crust is not a homogeneous substance. It has. different layers of rocks including sedimentary rocks on the top. granitic and metamorphic rocks in the middle and basaltic rocks on the bottom. 4) Biosphere! The biosphere have all the zones on the earth to which life is present. In other words, the biosphere is defined as the region on. above and below the earth's surface where life exists. It develops on earth since 4.5 billions year through evolutionary process. At the top of the lithosphere throughout the hydrosphere and into the lower atmosphere life of diverse types exist. Inorganic chemicals H2O, N2, COD, CH4, NH39 (Prebiotic Fnergy (Uv lighting) organic synthesis) Simple organic compound (Segregation, Organic macromolecules. organisation and replication) Protocells Living cells (Steps to origin of Life) Protocells are not living organisins. their features show that they have similar character as biological cells. The steps involved in the origin of life on earth is very complex and requires several centuries. The earliest organisms on the earth were heterotropic prokaryotic bacteria. Subsequently awotrophic prokaryotics and Pukaryotes start appearing as stepwise evelestionary charges. Life on earth requires water, a source of energy (sunlighe) and various nutrients found in the soil, water and air. Suitable combinations of these essentials cannot be found in high in the tipper atmosphere or deep under ground. They exist only in a narrow layer near the surface of the earth. This biosphere layer extends over most of the surface of the earth. Living organisms are not distribution uniformly on globe few organisms live on poler ice cups and glaciers where as many live in tropical rainforest.