Greenhouse effect is a process of trapping heat in the atmosphere. The term greenhouse is given to a glass house constructed to keep delicate and rare plants that require warmth and protection from weather. The glass walls allow sun rays and heat to pass into the glass house. The heat that enter the glass house cannot escape out, because the glass walls radiate back the heat inside the glass house. This makes the glass house warmer than the outside environment and the phenomenon is termed as “greenhouse effect”. Similar phenomenon occurs on the earth when the heat is not allowed to radiate back in the space.
GLOBAL WARMING. Addition of certain gases such as carbon dioxide, methane, water vapour, chlorofluorocarbons etc to the atmosphere has been rising at a speed never witnessed earlier in the history of earth. These gases are known to trap long wave infrared radiations emitted by earth. Due to steady increase in the concentration of greenhouse gases, the temperature of the earth has risen by almost one degree Fahrenheit which is termed as “global warming”. It has become a cause of worry as it has a far reaching effect on quality of the environment.
▪Our earth receives most of it’s energy from the sun. This energy is electromagnetic radiation in the visible spectrum with small amounts of IR and UV radiation.
▪The incoming solar energy has a very short wavelength and passes through the atmospheric gases unaffected to reach the earth’s surface.
▪The earth’s surface absorbs the solar energy and releases it back to the atmosphere as infrared(IR) radiation, some of which goes back into space.
▪Some of the IR radiation emitted by the earth is absorbed by gases in the atmosphere that re- emit the energy as heat back towards the earth’s surface.
▪The three main gases carbon dioxide, methane and water absorb the IR radiation emitted by the earth and re – radiate the energy as heat back towards the earth causing greenhouse effect. This has caused a dangerous global warming process that is threatning our current environment by melting polar ice caps and raising sea levels around the globe. The human beings would be more vulnerable to diseases as increased temperature would increase viruses, parasites and insects as all these thrive better in warmer conditions.