Greenhouse gases surrounding us..Horrible

Our wonderful earth constantly receives energy mostly from sun but some is through radioactive processes within earth itself. It also radiates energy to outer space. The earth is covered by a layer of atmosphere. The atmosphere is used to regulate the temperature of the earth. The earth will become cold and lifeless as Mars without atmosphere.

However, the presence of atmosphere can contain gases that absorb and emit infrared radiation which causes the greenhouse effect happen. The greenhouse effect heats the surface of the earth. The presence of greenhouse gases cause the greenhouse effect. Common greenhouse gases:carbon dioxide, methane, nitrous oxide,fluorocarbons...These gases are almost transparent to solar radiation.

The common greenhouse gases:

Carbon dioxide(CO2)-major greenhouse gas

Carbon dioxide is colourless and odourless. It is non-flammable gas. Carbon dioxide is absorbed by the plants during the photosynthesis process. Photosynthesis process is important for green plants and other organisms. Conversion of light energy into chemical energy occurs. Besides that, carbon dioxide also release to the air through our human exhalation and human activity. Such as the burning fossil fuels for energy and deforestation. When we burn the fossil fuels, the carbon within it will combine with oxygen and form carbon dioxide. Therefore, the concentration of carbon dioxide keep on increasing throughout years.

Water vapour-most abundant

It is greatly affect the temperature of the earth. The condensation of water vapour to the liquid forms clouds,rain,snow and others. As the temperature of the atmosphere rises, more water is evaporated from ground storage (rivers, oceans, reservoirs, soil). The relative humidity will raise due to the air is warmer which results more water vapor in the atmosphere. Therefore, the higher concentration of water vapor is able to absorb more thermal infrared energy radiated from the earth. The atmosphere becomes warmer and it can hold more water vapour.

Methane(CH4)-flammable(swamp gas)

Methane is colourless and odourless and very effective in trapping heat in the atmosphere compare to carbon dioxide. It is produced by plants decay. Besides that,bacteria which breaks down the organic matter in wetlands and bacteria that are found in cows, sheep, goats, buffalo, termites, and camels produce methane naturally.Methane is used as the fuel. The combustion of methane is highly exothermic.It will release the energy in the form of natural gas. It is used to heat homes and commercial buildings and the generation of electric power.

Nitrous oxide(laughing gas)N2O

Nitrous oxide also a colourless gas but it has sweet odour. Commonly, the heating of ammonium nitrate will produce nitrous oxide. The ammonium nitrate will decompose into nitrous oxide and water vapour.NH4NO3 (s) → 2 H2O (g) + N2O (g). The sources of N2O also come from human activity or natural. The concentrations of nitrous oxide are increasing due to the industrial revolution and the microbial processes in soil and water.

ozone(O3)-triatomic molecule

It consists of three oxygen atoms. When ultraviolet radiation interact with oxygen,it will form ozone. The exhaust emissions from automobiles and pollution from factories leads to greater concentrations of carbon and nitrogen molecules in the lower atmosphere. Therefore, when the carbon and nitrogen molecules are acted on by sunlight, it will produce ozone. Ozone is an important contributor to photochemical smog.

chlorofluorocarbon(CFCs)-Freon

They are non-toxic, non-flammable and non-carcinogenic. They are composed of fluorine atoms, carbon atoms and chlorine atoms.

The 5 main CFCs:

CFC-11 (trichlorofluoromethane - CFCl3)

CFC-12 (dichloro-difluoromethane - CF2Cl2)

CFC-113 (trichloro-trifluoroethane - C2F3Cl3)

CFC-114 (dichloro-tetrfluoroethane - C2F4Cl2)

CFC-115 (chloropentafluoroethane - C2F5Cl)

They are widely used as refrigerants, aerosol propellants,cleaning solvents and others. Therefore,all of these have increased the concentrations of CFCs in the atmosphere and caused the stratospheric ozone depletion. In addition, CFCs have a long lifetime in the atmosphere. One free chlorine atom from a CFC molecule can do a lot of damage. It can destroy ozone molecules for a long time.