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  1. The thick layer of air that surrounds the earth's crust is called atmosphere.

  2. Troposphere is responsible for the change of weather because various activities related the weather like cloud formation, lightening, rain, forest, hailstorm, fog, etc. occurs in this layer.

  3. The layer of pale blue gas (O3) present in the stratosphere that absorbs about 99% of harmful solar radiation like UV rays, x-rays, etc. is called ozone layer.
    Ozone layer is also called the protective layer because it protects earth from harmful ultraviolet radiation. Ozone layer not only absorbs ultraviolet radiation but also radiations of wave length less then 3x10-7m. It prevents us from dangerous diseases like cataracts (blindness), skin burning, skin cancer and immune deficiency. It helps to balance the weather and temp. of the earth and to reduce the greenhouse effect.

  4. Ozone formation is a natural process, which is formed by the combination of 3 oxygen atoms due to the influence of ultraviolet radiations. When an oxygen molecules absorbs high energy solar radiation it dissociates into nascent oxygen. The nascent oxygen is highly reactive and thus combines with oxygen molecules and forms the molecules of ozone.
                                O2 -------------> [O] + [O]  (Nascent)
                                O2 + O --------------> O3 Ozone

  5. Decreasing the thickness of ozone layer or formation of hole in it is called ozone layer depletion. 

  6. The adverse effects of ozone layer depletion are:
            - In human beings, UV rays causes various diseases like cataract (blindness), sun burn, eye burn, skin cancer, leukemia, etc.
            - It causes mutation in different generations.
            - It hampers the growth and development of plants and animals.
            - It causes greenhouse effect and global warming.
            - It cause many species to be extinct.
            - It causes the climate change.

  7. - Mechanism of ozone layer formation:
                            O2 -----------> [O] + [O]  (Nascent Oxygen)
                            O2 + O -----------> O3  (Ozone)

    - Mechanism of ozone layer depletion:
                            CFCl3 ----------> CFCl2 + Cl
                            Cl + O3 -----------> O2 + ClO
                            2ClO ------------> 2Cl + O2

  8. The steps to prevent ozone layer depletion are:
            - Alternative chemicals should be used instead of CFCs.
            - The production and use of chlorofluorocarbons and oxides of nitrogen should be banned.
            - Public awareness should be generated about ozone layer depletion and its protection.
            - Afforestation programs should be encouraged.
            - Production of greenhouse gases should be stopped.
            - Use of chemical fertilizers should be banned.

  9. Various toxic gases like CO2, SO2, SO3, NO, NO2, N2Os, etc. which are released by industries are called industrial gases.
    Their adverse effects are:
            - It results in ozone layer depletion.
            - It hinder human muscular and mental functioning.
            - It causes various diseases like pneumonia, eye diseases, bronchitis, etc.
            - It results in the pollution of atmosphere.

  10. Troposphere is called the variable sphere because its temperature varies according to its height. It decreases as the height increases.

  11. The uppermost part/layer of the stratosphere contains the ozone layer. This thick layer of air absorbs much of the solar radiation. Due to absorption of the solar radiation, the temp. of the stratosphere increases as the height increases.

  12. The uppermost layer of stratosphere contains the ozone layer. This thick layer of air absorbs much of the solar radiation and shields the earth from the harmful ultraviolet radiation. It prevents us from dangerous diseases. Therefore, the stratosphere is called a protective umbrella.

  13. The lower region of the thermosphere contains ions of nitrogen, oxygen, etc. The gaseous molecules like nitrogen, oxygen, etc. undergo ionization and gives ions due to the effect of UV radiation of sun. Therefore, thermosphere is also called ionosphere.

  14. Exosphere is called fringe region because it forms the outermost edge of the atmosphere.

  15. As we know, the production and use of CFCs increases the amount of CFC in atmosphere that react with ozone and deplete the layer of ozone. So, to prevent the depletion of ozone layer, the production and use of CFCs must be avoided.

  16. Climate change a change in the statical distribution of weather patterns when that change lasts for an extended period of time, i.e. decades to millions of years.

  17. Any four causes of climate change are:
            - Global warming.
            - Release of greenhouse gases.
            - Deforestation.
            - Excessive use of chemical fertilizer.
            - Industrialization.
            - Volcanic eruption.

  18. The major effects of climate change are:
            - It causes loss of biodiversity.
            - It decreases agricultural production and change crop pattern
            - It melts snow in the popular region and the Himalayan region.
            - It increases sea level due to the melting of ice in the polar region.
            - It decreases the amount of fresh water.
            - It affects the global water cycle.
            - It causes improper distribution of rainfall.

  19. The names of org. involved in climate change management are:
            - WWF
            - IUCN
            - UNESCO

  20. The national efforts for the reduction of and adaption to climate change are:
            - National Communication Report.
            - Climate change policy, 2067.
            - Climate change Adaption Strategic Program.
            - National Adaption Program.

  21. The international efforts are:
            - The United Nations Framework Convention of Climate Change (UNFCCC).
            - UN Climate change conference.
            - Agenda 21.
            - Intergovernmental forum.
            - Kyoto Protocol.
            - Measures to reduce GHG on the basis of Kyoto Protocol.
            - Reduction of emission due to deforestation.

  22. Climate change causes increase in atmospheric pressure and temperature. The Increase in temperature has negative impacts on agriculture, forests, human health, bio-diversity, socio-economic aspects, etc. in Nepal. Thus, it is essential to generate awareness regarding the ways to adapt to climate change and its effects. In this regard Climate Change Policy, 2067 has been developed with the specific objectives and policies.

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