A glass house used for raising delicate plants is called Green House. A green house has higher temperature inside than outside though the interior receives less radiations. It is called Green House Effect. The factors which contribute to this effect are (i) glass walls (ii) high carbon dioxide content and (iii) high water vapour content of the air in the Green House. They let the short wave radiations (wave length 0.15-4.0 pm) pass through them but prevent the passage of long wave (infra red) radiations emitted by the earth’s surface. This makes inside of the Green House warmer than outside.
In the context of environment, Green House effect refers to ‘selective energy absorption by some atmospheric gases, which allow short wave length energy to pass through but absorbs longer wave lengths and reflect heat back to earth’. The atmospheric gases which are permeable to short wave solar radiations, but are strong absorber of long wave radiations emitted from the surface of earth are called Green House gases. These include carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, ozone and water vapour. Though carbon dioxide contributes maximum to the Green House effect on the earth, methane (CH) and chlorofluoro carbons (CJ Cs) are potent Green House gases even though their contributions in the atmosphere are much less than that of carbon dioxide. Carbon dioxide is chiefly produced by the burning of fuels. It is also released by plants and animals during the process of respiration. Methane is the primary component of natural gas and it emanates from garbage dumps, swamps and rice fields. Chlorofluorocarbons are used around the world as refrigerants, aerosol propellants, in isulators and fire extinguishers. These gases are responsible for about 15 per cent of the green House Effect.
Nitrous oxide (N2O) is produced during the process of destruction of ozone layer in the stratosphere. The ozone in the stratosphere acts as a protective layer, because it absorbs much of the ultra violet radiation from the sun. however, its higher Concentration in troposphere acts as a Green House gas. It is responsible for about 10-20 percent of the Green House effect.