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Greenhouse effect
- 1. GUIDED BY- Dr. JAMESMATTHEW SUBMITTEDBY- NEHA MISHRA (M.Sc. 4TH sem.)
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- 3. Greenhouse abuilding made mainly of glass, with heat & humidity regulated for growing plants. The atmosphere acts like a glass in a greenhouse. Atmosphere, like glass absorbs some of the long wave radiation emitted by earth and radiates the energy back to earth. In this way temperature of earth is maintained. The atmosphere surrounding the earth in this manner plays a vital role in maintaining an even temperature on the earth’s surface. A greenhouse is that body which allows the short wavelength incoming solar radiation to come in, but does not allow the long wave outgoing terrestrial infrared radiation to escape.
- 4. Earth’s atmospherebottles up the energy of the sun, & is said to act like a greenhouse. Carbon-dioxide present in the atmosphere acts like glass windows. Carbon-dioxide and water vapours in the atmosphere transmit short wavelength solar radiation but reflect the longer wavelength heat radiation from warmed surface of the earth. Carbon-dioxide molecules are transparent to sunlight but not but not to the heat radiation. They trap the re-enforce the solar heat. The Greenhouse effect defined as the progressive warming up of the earth’s surface due to blanketing effect of manmade CO2 in the atmosphere.
- 8. The fourmajor greenhouse gases, which causes adverse effects are carbon-dioxide, methane, nitrous oxide and chlorofluorocarbon. For the earth, water vapour is the most important of all greenhouse gases. Water vapour absorbs IR in the region 2.5 to 3.5 µm 5 to 7 µm, as well as over a broad range above 13 µm. CARBON-DIOXIDE It is a major contributor to greenhouse effect because it absorbs IR in the range of 14 to 19 µm, and completely blocks the radiation flux between 15 to 16 µm. The burning of fossil fuels such as coal, tar, and natural gases release CO2 . Burning of wood, waste materials and tress release CO2.
- 9. METHANE Methane absorbradiation in the wavelength ranges from 3 to 4 µm and 7 – 8.4 µm (in the window region). Methane gas increases stratospheric water vapour on oxidation and the rise in water vapour is more important source of greenhouse effect than the direct effect of methane gas. NITROUS OXIDE Nitrous oxide absorb IR radiation in the ranges 3 to 5 µm and 7.5 to 9 µm (infrared window). The major sources of nitrous oxide are microbial denitrification, conversion of nitrate to nitrous oxide soils, lake and oceans. Methane gas is 24 times & nitrous oxide is around 320 times aggressive greenhouse gas than carbon dioxide.
- 10. CHLOROFLUROCARBONS (CFCS) CFCsabsorb in the range 8 to 12 µm with each CFC having specific absorption bands in the region. CFCs are released into the atmosphere during the operations and maintenances of appliances and equipments using these molecules as coolants and propellants. HYDROCHLOROFLUROCARBONS (HCFCS) The HCFCs also attenuate radiation within the same range, but their in the troposphere is much shorter than that of the CFCs. The rate of increase of CFCs has declined by a factor greater than two in the past decade, but HCFC concentrations are increasing at a much higher rate.
- 14. The greenhouse effectwill bring about the following important changes in the climate of the Earth. As a result of rise in temperature of the earth due to greenhouse effect the oceans get warm up and sea level would rise flooding low lying regions. In temperate regions, the winter will be shorter and warmer and the summer will be longer and hotter. There will be enormous increase in rainfall but the problems of desertification, drought and soil erosion will further worsen. The tropics may become wetter and the subtropics, which are already dry, are expected to be drier. The plants & animals will also be affected resulting in the disruption of the whole ecosystem.
- 16. Erik M.Conway(2008) defined global warming as “the increase in Earth’s average surface temperature due to rising levels of greenhouse gases”. Global warming will lead to higher temperature and changes in rainfall, and this in turn will modify the extent and productivity of land suitable for agriculture. • For example, a temperature increase of 3ºC paired with a rainfall increase of 10% in the developing countries would cause a decrease of 11% productivity that could have serious consequences for food security. According to latest climate change report, global warming would decrease crop production in developing countries but increase in industrialised world. Global warming would also have short term and long term effects on human health and environment.
- 18. The hotdays are sure to be scorching and cold ones freezing. In future, the rain is going to be intensive. Changes in frequency & intensity of extreme weather will have profound impact human society and natural resources. A few study forecast an increase in the number of deep cyclones and increase in intensity of the storm over western Europe. With the continuing increase in greenhouse gases in the 21st century, the losses caused by natural calamites and catastrophes are bound to increase. A century from now, the Earth’s surface will be about 3.5ºC higher than in 1990.
- 19. Surface oceanwaters today are roughly 30 percent more acidic than at the start of the Industrial Revolution. In the last decade, the rate of Antarctica's ice mass depletion has tripled. Scientists predict that the Arctic Ocean will barely have ice before 2050. For the last twenty years, sea levels rose at twice their rate during the last century. Global temperatures could increase by as much as 10.4 degrees Fahrenheit by 2100.
- 22. https://www.britannica.com/science/global-warming https://en.wikipedia.org/wiki/Global_warming Book- Environmental chemistry, By B.K. Sharma, 12th edition(2015), Page no.- 141 – 196. Book- Environmental chemistry, By A.K. De, 7th edition (2010), Page no.- 32 – 41.