[Chemistry Class Notes] Greenhouse Gas Pdf for Exam

In this article, we have discussed greenhouse gases’ meaning. This article will help the students in making a short note on greenhouse gases. This Greenhouse effect article will help the students in clearing the concepts of greenhouse gases and global warming.

Greenhouse Gases Definition– Greenhouse gases definition explains the meaning of greenhouse gas. These are the gases that absorb and emit infrared radiation in the wavelength range emitted by the earth. 

Let’s discuss which gas is called greenhouse gas? The examples of greenhouse gases in the earth’s atmosphere are: 

Examples of greenhouse gases such as carbon dioxide (CO2) and water vapour (H2O) are natural greenhouse gases. Examples of greenhouse gas such as methane are anthropogenic emission greenhouse gases. 

Contribution of Greenhouse Gases

89 % is contributed by the water vapour, 7 % is contributed by carbon dioxide, and the remaining percent is contributed by the other mentioned gases in the table.

What are Greenhouse Gas Emissions?

Greenhouse gas emissions are the emission of gases from various sources that cause global warming. The major emission source of greenhouse gases is an energy source and the least is contributed by the solvents.

Percentage contribution to Global Warming 

Before discussing this let’s discuss what is meant by greenhouse gases? Greenhouse gases are harmful environmental gases that are responsible for causing global warming.

Contribution 

Carbon dioxide (CO2) > Methane (CH4) > Chlorofluorocarbons (CFCS) > Nitrous oxide (N2O)

Carbon dioxide contribution = 60%

Methane contribution = 20%

Chlorofluorocarbons contribution = 14%

Nitrous oxide contribution = 6%

Water vapour is not listed due to the amount being variable in nature and not anthropogenic.  

Why is the Study of Greenhouse Gases necessary?

The answer to this question is similar to the question: what is the meaning of greenhouse gases? The greenhouse gases like methane, nitrous oxide, chloro fluoro carbons increases day by day due to the anthropogenic activities which trap the radiation of wavelength (7 to 13 micrometres) come under the atmospheric window and re-radiated back to the atmosphere and increase the temperature of the earth.

1. Carbon Dioxide

Absorbs radiation between 4 to 5 micrometre and 14-19 micrometre.

Concentration in pre-industrial time was 280 parts per million and in present-day its concentration is around 400 parts per million.

Residence time for carbon dioxide is 5 years to 200 years.

2. Methane 

Methane absorbs radiation between 3 to 5 micrometre and 7 to 8.5 micrometre.

Concentration in pre-industrial time was 750 parts per billion and in present-day it is around 1800 parts per billion.

3. Nitrous Oxide

Nitrous oxide absorbs radiation between 3 to 5 micrometre and 7.5 to 9 micrometre.

Concentration in pre-industrial time was 7270 parts per billion and in present-day it is around 330 parts per billion.

4. Tropospheric Ozone

Ozone absorbs edition between 9-10.6 micrometre 

Its concentration varies from place to place.

5. Halocarbons

Halocarbons absorb radiation around 9 micrometre in the frequency of the atmospheric window so that these are potent greenhouse gases and also play a role in depleting stratospheric ozone.

It can be divided into five categories:

• Chlorofluorocarbons (CFCs)

• Hydrochlorofluorocarbon (HCFCs)

• Hydro Fluoro Carbon (HFCs)

• Perfluorocarbon (FCs)

• Halones

The ozone-depleting potential of halocarbons is

Global Warming Potential (GWP)

Global warming potential is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It allows a comparison to be made between the global warming impact over a specified particular GHGs and simultaneous emission of an equal mass of carbon dioxide (CO₂). 

Order of magnitude of Global Warming Potential

Sulphur hexafluoride (SF6) > Halocarbons > nitrous oxide (N2O) > methane (CH4)> carbon dioxide (CO2).

Did You Know?

• Water provides a major contribution to the total greenhouse gases. Still, its contribution is not countable in causing global warming due to its variable concentration in the atmosphere.

•  The area of the electromagnetic spectrum where the atmosphere is transparent to specific wavelengths between 7 to 13.5 micrometers is called an atmospheric window.