Ozone Layer

11. Montreal Protocol ratifies:

Montreal Protocol ratifies:

restricting the production of CFCs.
sustainable development.
carbon trading.
restricting the global average temperature below 2 °C above the pre-industrial level.
This question was previously asked in
UPSC Geoscientist – 2021
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The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production and consumption of ozone-depleting substances, most notably chlorofluorocarbons (CFCs).
Ratified in 1987, the Montreal Protocol is considered one of the most successful international environmental agreements. Its implementation has led to a significant reduction in the emission of ODS and the slow recovery of the ozone layer.
Sustainable development is a broader concept. Carbon trading and the goal of restricting global temperature increase below 2 °C are associated with efforts to combat climate change, primarily through the Kyoto Protocol and the Paris Agreement, respectively, not the Montreal Protocol.

12. Which one among the following is true about Ozone Hole?

Which one among the following is true about Ozone Hole?

It is the loss of Tropospheric ozone over Antarctica
It is the loss of Stratospheric ozone over Antarctica
It is a hole in the Antarctic ice sheet created due to ozone
It is the loss of equatorial ozone
This question was previously asked in
UPSC Geoscientist – 2021
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The “Ozone Hole” refers to the significant thinning or depletion of the protective stratospheric ozone layer, primarily observed over the Antarctic region during the spring (August-October).
The stratospheric ozone layer absorbs most of the Sun’s harmful ultraviolet (UV) radiation. Its depletion, mainly due to human-produced chemicals like CFCs and halons, leads to increased UV radiation reaching the Earth’s surface.
Ozone depletion also occurs over the Arctic, but the phenomenon is more severe and consistent over Antarctica due to specific atmospheric conditions (polar vortex and polar stratospheric clouds). Tropospheric ozone is a greenhouse gas and an air pollutant, harmful to human health and ecosystems, and is distinct from the stratospheric ozone layer.

13. Ozone layer depletion is concentrated in:

Ozone layer depletion is concentrated in:

mid-latitude regions.
high latitude regions.
equatorial regions.
tropical regions.
This question was previously asked in
UPSC Geoscientist – 2020
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Ozone layer depletion is most significantly observed in the high latitude regions, particularly over the Antarctic (forming the ‘ozone hole’) and to a lesser extent over the Arctic.
– Ozone depletion is concentrated at the poles.
– This phenomenon is driven by chemical reactions involving ozone-depleting substances (like CFCs) which are catalyzed on the surface of polar stratospheric clouds (PSCs) that form at very low temperatures in the polar stratosphere during winter.
– The depletion becomes pronounced in spring when sunlight returns, initiating the catalytic cycles.
– While ozone depletion occurs globally to some extent, the most severe and rapid depletion occurs in the high latitudes.
– Mid-latitude depletion is less severe than polar depletion.
– Equatorial and tropical regions experience relatively less ozone depletion due to different stratospheric temperature and circulation patterns.

14. Ozone hole is a region over :

Ozone hole is a region over :

the Antarctic caused mainly by CFC gases.
the Antarctic caused mainly by carbon dioxide gas.
the Arctic caused mainly by CFC gases.
the Arctic caused mainly by carbon dioxide gas.
This question was previously asked in
UPSC CDS-2 – 2024
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The ozone hole is a region over the Antarctic caused mainly by CFC gases.
The “ozone hole” refers to the dramatic thinning of the stratospheric ozone layer that occurs annually over Antarctica during the Southern Hemisphere spring (August-October). This severe depletion is primarily driven by catalytic reactions involving chlorine and bromine atoms released from synthetic ozone-depleting substances (ODS) like chlorofluorocarbons (CFCs) and halons, which accumulate in the stratosphere and are activated under the extremely cold conditions and sunlight present in the Antarctic polar vortex.
While some ozone depletion also occurs over the Arctic, it is generally less severe and variable due to different meteorological conditions. Carbon dioxide (CO₂) is a greenhouse gas that contributes to global warming but is not a direct cause of stratospheric ozone depletion; in fact, increasing greenhouse gases can even cool the stratosphere, potentially influencing ozone chemistry in complex ways.

15. Which one of the following statements with regard to ozone is not

Which one of the following statements with regard to ozone is not correct?

Ozone is found mostly at 15-55 km in the atmosphere.
Ozone is produced by gaseous chemical reactions.
16th November is celebrated as the International Day for the Preservation of the Ozone Layer.
Ozone is a form of oxygen in which three oxygen atoms are bounded together.
This question was previously asked in
UPSC CDS-2 – 2020
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The statement “16th November is celebrated as the International Day for the Preservation of the Ozone Layer” is not correct.
The International Day for the Preservation of the Ozone Layer is celebrated annually on September 16th. This date commemorates the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987.
The other statements are generally correct: Ozone is found predominantly in the stratosphere (the ozone layer), roughly between 10 km and 50 km altitude, with the highest concentration typically between 15 and 35 km, making the range 15-55 km acceptable. Ozone (O₃) is indeed a molecule formed by three oxygen atoms bonded together, and it is produced through photochemical reactions involving oxygen molecules and atoms in the atmosphere, particularly by UV radiation.

16. Ozone layer, which absorbs the ultra-violet radiation, is found in whi

Ozone layer, which absorbs the ultra-violet radiation, is found in which one of the following layers of the atmosphere ?

Ionosphere
Troposphere
Mesosphere
Stratosphere
This question was previously asked in
UPSC CDS-1 – 2021
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The ozone layer, which plays a crucial role in absorbing harmful ultraviolet (UV) radiation from the Sun, is primarily located in the stratosphere. This layer of the atmosphere is found above the troposphere and extends to about 50 kilometers above the Earth’s surface.
– The atmosphere is divided into several layers: Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere.
– Each layer has distinct characteristics regarding temperature profile and composition.
The troposphere is the lowest layer where most weather occurs. The mesosphere is above the stratosphere, and temperature decreases with height. The ionosphere is part of the thermosphere and upper mesosphere, characterized by ionized gases important for radio communication.
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