The thick layer of air that surrounds the earth'scrust is called atmosphere.

Troposphere is responsible for the change of weatherbecause various activities related the weather like cloudformation, lightening, rain, forest, hailstorm,fog, etc.occurs in thislayer.

The layer of pale blue gas (O₃) present in thestratosphere that absorbs about 99% of harmfulsolar radiation like UV rays, x-rays, etc. is called ozone layer.
Ozone layer is also called the protectivelayerbecause it protects earth from harmfulultravioletradiation. Ozone layer not only absorbsultravioletradiation but also radiations of wave length less then3x10^-7m. It prevents us from dangerous diseases likecataracts(blindness), skin burning, skin cancer andimmune deficiency. It helps to balance...

Ozone formation is a natural process, which is formedby the combination of 3 oxygen atoms due to the influenceof ultravioletradiations. When an oxygen moleculesabsorbs high energysolar radiation it dissociates intonascent oxygen. The nascent oxygen is highly reactiveand thus combines with oxygen molecules and forms themolecules of ozone.
O₂ -------------> [O] + [O] (Nascent)
O₂ + O --------------> O₃ Ozone

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

The adverse effects of ozone layer depletion are:
-In human beings, UV rays causes various diseaseslike cataract (blindness), sun burn, eye burn, skincancer, leukemia, etc.
-It causes mutation in different generations.
-It hampersthe growth and development of plantsand animals.
-It causes greenhouse effect and global warming.
-It cause many speciesto be extinct.
-It causes the climate change.

- 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

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

Various toxic gaseslike CO₂, SO₂, SO₃, NO, NO₂, N₂Os, etc.which are released by industries are called industrialgases.
Their adverseeffects are:
-It results in ozone layer depletion.
-It hinder human muscular and mental functioning.
-It causes various diseaseslike pneumonia, eye diseases, bronchitis, etc.
-It resultsin the pollution of atmosphere.

Troposphere is called the variable sphere because itstemperature varies accordingto its height. It decreasesas the height increases.

Theuppermost layer of stratosphere contains the ozonelayer. This thick layer of air absorbs much of the solarradiation and shields the earth from the harmfulultraviolet radiation. It prevents us from dangerousdiseases. Therefore, the stratosphere is called aprotectiveumbrella.

The lower region of the thermosphere contains ions ofnitrogen, oxygen, etc. Thegaseousmolecules like nitrogen,oxygen, etc. undergo ionization and gives ions due tothe effect of UV radiationof sun. Therefore, thermosphereis also called ionosphere.

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

As we know, the production and use of CFCs increasesthe amount of CFC in atmosphere that react with ozoneand deplete the layer of ozone. So, to prevent the depletion of ozone layer, the production and use of CFCsmust beavoided.

Climate change a change in the statical distributionof weather patterns when that change lasts for anextended period of time, i.e. decades to millions ofyears.

Anyfour causes of climate change are:
-Global warming.
-Release of greenhouse gases.
-Deforestation.
-Excessiveuse of chemical fertilizer.
-Industrialization.
-Volcanic eruption.

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

The names oforg.involved in climate changemanagement are:
-WWF
-IUCN
-UNESCO

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

The international efforts are:
- The United Nations Framework Convention of ClimateChange (UNFCCC).
-UNClimatechange conference.
-Agenda 21.
-Intergovernmental forum.
-KyotoProtocol.
-Measures to reduce GHG on the basis of KyotoProtocol.
-Reduction of emission due to deforestation.

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