Green House effect:
The trapping of the sun’s warmth in a planet’s lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet’s surface.
Global Warming is the increase of Earth’s average surface temperature due to effect of greenhouse gases, such as carbon dioxide emissions from burning fossil fuels or from deforestation, which trap heat that would otherwise escape from Earth.
- The progressive heating up of surface of the earth is called greenhouse effect or global warming.
- CO₂ & H₂O block a part of the heat (IR) emitted by the earth & reflect back. Due to this earth surface gets heated up.
- 50% in CO₂ content of air can increase the surface temperature of the earth by 30˚C.
- In addition to CO₂, the other green – house gases are CFC’s (17%), O₃ (18%), NO (4%), water vapour (2%).
Consequences of Global warming:
- Increases the temperature of the earth and creates disturbances to life cycle of all living forms.
- The ice caps of the polar region melt, increasing the level of the sea water. As a result many countries will get submerged.
- Unseasonal rains, cyclones & hurricanes occur due to increase of rate of evaporation of water.
- The level of ground water decreases and agriculture sector will be badly affected.
- Global warming can be prevented by increasing the number of sinks of CO₂ (like plants).