Green House Effect

The green house effect is produced by carbon dioxide gas present in the atmosphere of earth. We have studied that sunlight consists 3 types of rays;

1. Ultraviolet rays
2. Visible light and
3. Infra-red rays

The infra red rays emitted by the sun are usually of short wavelength. The carbon dioxide gas present in the atmosphere allows these short wavelength infra red rays to pass through it. After passing through carbon dioxide when infra red rays reach the surface of earth, some of these rays heat the objects present on the surface of earth, while others get reflected back in the atmosphere. But, the infra red rays reflected by earth are of longer wavelength as compared to those emitted by sun. So, carbon dioxide does not allow these longer wavelength infra red rays to pass through it and absorbs them. Due to absorption of these longer wavelength infra red rays by carbon dioxide the temperature of atmosphere of earth rises and it becomes hot. This is called green house effect or global warming.

Green House Gases
The gases which can trap the infra red rays coming from sun are called green house gases.

Examples of Green House Gases:
There are many gases in atmosphere which contribute in green house effect. For example, ozone gas (O₃), methane gas (CH₄), chloro fluoro carbons, and carbon dioxide (CO₂). Among these gases carbon dioxide (CO₂) is regarded as the most important green house gas.

Effects of Global Warming/ Green House Effect:
The increase in the temperature of earth can have following adverse effects:

1. The summer will be longer and hotter and winter will be shorter and warmer.
2. The number of days having intense temperature and rainfall will increase.
3. Due to global warming the ice caps in polar areas will start melting causing floods in rivers and rising of the level of oceans. The rise in level of oceans can submerge the countries or cities established near coastal areas.
4. Hurricanes and storms will be stronger and more frequent.
5. Global warming will also affect human health. Global warming will cause respiratory diseases, dengue and malaria in human beings.

Test Your Understanding and Answer These Questions:

1. What is the green house effect?
2. What causes global warming?
3. What are green house gases?
4. What are the effects of global warming?