Green house Gases

Green house gases

•The primary components of Earth’s atmosphere, N2 and O2 do not have absorption in the IR wavelength range, therefore, do not have a significant role in setting the surface temperature of the planet…•Greenhouse gas are efficient in absorbing IR light…

•The most important greenhouse gases are:•H2O – Water vapor.•CO2 – Carbon Dioxide•CH4 – methane•The most abundant greenhouse gas in Earth’s atmosphere is water vapor. Most of the greenhouse heating of Earth’s atmosphere is due to Water vapor absorption of IR radiation emitted by Earth, and then transferring the energy to the surrounding air molecule

GHG GWP in 100 years

CO2 1

CH4 23

N2O 310

PFC 9,200

HFC 140 to11,700

SF6 23,900

Global-warming potential (GWP) is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide. A GWP is calculated over a specific time interval, commonly 20, 100 or 500 years. GWP is expressed as a factor of carbon dioxide (whose GWP is standardized to 1). For example, the 20 year GWP of methane is 72, which means that if the same mass of methane and carbon dioxide were introduced into the atmosphere, that methane will trap 72 times more heat than the carbon dioxide over the next 20 years.[1]

GWP

The GWP depends on the following factors:

• The absorption of infrared radiation by a given species.

• The spectral location of its absorbing wavelengths

• The atmospheric lifetime of the species

Green house effect is due to Green house gases.

Sources :• Volcanic out gassing.• burning of organic matter.• Respiration by living organisms.

Properties CO2 :• It is a colorless gas.• It condenses into solid form (dry ice) at -78°C in atmospheric pressure.• Condenses into liquid at -57°C at pressure above 5.1 atmospheric pressure. • It is Highly soluble in water.

CO2

H2O vapors

Sources :•Surface water•Ground water•Rainwater

Properties :•it exists in liquid, solid, and gaseous states.•At room temperature, it is a tasteless and odorless liquid•It is referred to as the universal solvent.•Water has a neutral pH.

CH4Sources :•anaerobic decay of organic matter•geological deposits•animal husbandry•rice cultivation etc.

Properties :Physical•Methane is a colourless, odourless gas which is lighter than air.•It is a non-polar molecule and is insoluble in water.•It dissolves in non-polar solvents like alcohol, carbon tetrachloride, etc.•It is a renewable source of natural gas since it comes from decaying garbage.Chemical •Methane burns in air with a blue flame. •Methane is quite unreactive, except with fluorine, chlorine, etc. With these it undergoes substitution reactions.•Methane undergoes oxidative pyrolysis to form carbon monoxide

2006–2009 methane concentration in the upper troposphere

N2O

Sources:•Nitrous oxide is emitted by bacteria in soils and oceans.•Agriculture is the main source of human-produced nitrous oxide.•The livestock sector (primarily cows, chickens, and pigs) produces 65% of human-related nitrous oxide.•Industrial sources make up only about 20%

Properties :•Nitrous oxide is commonly prepared by deliberate heating of ammonium nitrate, which decomposes into nitrous oxide and water vapor.•Nitrous oxide commonly known as "laughing gas", has been used since long period to relieve pain and anxiousness during medical procedures