Greenhouse gas (GHG) is a gas in the atmosphere
that is capable of traping the infra red heat in the earth surface from
escaping to the outer space thereby increasing the temperature of the earth’s
surface. This is the basic
cause of the greenhouse effect. The major naturally occurring greenhouse gases in the
atmosphere are water vapour, carbon
dioxide, methane, nitrous
oxide and ozone.
Other GHGs produced as a result of
human industrial processes are hydrofluorocarbons (HFC), perfluorocarbons (PFC), and sulfur hexafluoride (SF6).
Water
Vapour :
Water vapour in the
atmosphere is directly propotional to the air temperature. When the temperature
increases, more water evaporates and
forms vapour in the atmosphere. Water vapour
being a green house gas, increase in the
water vapour adds to the greenhouse
effect, thus increasing the temperature. As the process is looped, scientists
call the effect as positive feedback loop.
Water vapour is considered the most dominant greenhouse gas as it magnifies the
temperature increase caused by other greenhouse gases.
Carbon
dioxide :
Combustion of
wood and fossil fuels, destruction of forest(trees help remove CO2) and volcanoes are the main causes of CO2 in the atmosphere.
Methane:
Methane
is released by the decomposition of organic matter in landfills, waste water
treatment, rice fields. Other sources include combustion of fossil fuels, volcanoes, fermentation from the
digestive system of livestock, glaciers, permafrost.
Nitrous
Oxide:
The main
source of nitrous oxide are fertilizers, manures used for agriculture,
combustion of fossil fuels.
Ozone:
Tropospheric ozone acts as a greenhouse
gas,The majority of tropospheric ozone formation occurs when the ozone precursors (nitrogen oxides (NOx), carbon
monoxide (CO) and volatile
organic compounds (VOCs)) react in the atmosphere in the presence of
sunlight. Fuel combustion from the motor vehicles, industrial emissions, and
chemical solvents are the main sources of the precursors.
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