GREEN HOUSE EFFECT & GLOBAL WARMING
The term green house effect had its origin from the practice of encasing vexampleetation in glass chambers to protect them from frost particularly in cold countries. It was observed that there was a continued rise in temperature in such chambers even when the outside temperature remains low. Thus enabled the warming up of inside the chamber, resulting in good plant growth.
Green house effect around the earth
Atmosphere around the earth acts like a glass of the green house chamber. The gases present in the atmosphere which cause green house effect are referred to as green house gases. The various green house gases are: 
vapours, chlorofluoro carbons and oxides of nitrogen.
The green house gases in the atmosphere form a thick cover around the earth. The earth receives a large amount of energy from the sun. The IR radiations coming from sun are not absorbed by atmospheric gases. The earth absorbs these IR radiations of short wavelength. As a result of this the temperature of earth stands rising. Eventually, earth starts emitting infrared radiations of longer wavelengths. The partially radiated infrared radiations from the earth are absorbed by This results in excessive heating of earths atmosphere. The heating of atmosphere due to absorption of infrared radiations by 
and other gases is called green house effect.
Advantages of green house effect
The presence of 
and other gases in the atmosphere produce green house effect, which in turn keeps the atmosphere warm. The warm atmosphere is very essential for survival of life on earth in the following ways:
(i) It is necessary for evaporation of water, formation of clouds, rainfall etc.
(ii) The warm atmosphere helps in rapid growth of plants, trees etc.
(iii) Warm atmosphere helps is biodexampleradation of dead plants and animals.
Harmful effects of green house effect
The disastrous consequences of green house effect are following:
(i) High temperature of atmosphere may melt polar ice caps which is likely to raise the level of sea thereby sinking most of the coastal areas and causing large scale destruction.
(ii) The high temperature may reduce crop product.
(iii) The high temperature will reduce work efficiency of human being.
(iv) Tropical rains and hurricane will become more frequent and also more stronger causing more devastation.
(v) The change in ocean temperature will adversely affect the warm life.
Illustration 1. What is not correct about green house effect?
(a) It results in global warming.
(b) is one of the main chemical species responsible for it.
(c) It results in lowering of levels of ocean over the years.
(d) 
also contribute to green house effect.
Solution:(C)
Illustration 2. Which main compounds are causing damage to ozone layer?
Solution: NO and freons
Illustration 3. Which acids are present in the acid rain?
Solution: H2SO4, HNO3 and HCl.
| « Click Here for Previous Topic | Click Here for Next Topic » |
Click Here to Go Back to CBSE Class 12 Eviornmental Chemistry All Topic Notes
Click Here for CBSE Class 12 Chemistry All Chapters Notes
To get fastest exam alerts and government job alerts in India, join our Telegram channel.
