Greenhouse Effect
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In general, the percentage of carbon dioxide in the atmosphere is 0.0345% (345 ppm).
But, due to the emission of pollutants and exhaust gases into the atmosphere, the percentage of carbon dioxide increases which forms a blanket in the outer atmosphere. This causes the entrapping of the reflected solar radiation from the earth surface. Due to this, the atmospheric temperature increases, causing global warming, melting of ice caps and rise in the ocean levels which result in the submergence of coastal lines. This phenomenon of increase in the ambient temperature, due to the formation of the blanket of carbon dioxide is known as global warming due to greenhouse effect. (An increase in the concentration of greenhouse gases in the atmosphere is termed as greenhouse effect.)


The greenhouse covering material acts in a similar way, as it is transparent to shorter wave radiation and opaque to long wave radiation. During the daytime, the short wave radiation enters into the greenhouse and gets reflected from the ground surface. This reflected radiation becomes long wave radiation and is entrapped inside the greenhouse by the covering material. This causes the increase in the greenhouse temperature. It is desirable effect from point of view of crop growth in the cold regions.


Greenhouse Effect
1. Advantages of Greenhouses

The following are the different advantages of using the greenhouse for growing crops
under controlled environment:
1. Throughout the year four to five crops can be grown in a greenhouse due to availability of required plant environmental conditions.
2. The productivity of the crop is increased considerably.
3. Superior quality produce can be obtained as they are grown under suitably controlled environment.
4. Gadgets for efficient use of various inputs like water, fertilizers, seeds and plant protection chemicals can be well maintained in a greenhouse.
5. Effective control of pests and diseases is possible as the growing area is enclosed.
6. Percentage of germination of seeds is high in greenhouses.
7. The acclimatization of plantlets of tissue culture technique can be carried out in a
greenhouse.
8. Agricultural and horticultural crop production schedules can be planned to take
advantage of the market needs.
9. Different types of growing medium like peat mass, vermiculate, rice hulls and compost that are used in intensive agriculture can be effectively utilized in the greenhouse.
10. Export quality produce of international standards can be produced in a greenhouse.
11. When the crops are not grown, drying and related operations of the harvested produce
can be taken up utilizing the entrapped heat.
12. Greenhouses are suitable for automation of irrigation, application of other inputs and
environmental controls by using computers and artificial intelligence techniques.
13. Self-employment for educated youth on farm can be increased.


Earth Greenhouse Effect