- Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location- changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.
What to study?
For Prelims and Mains: About Ozone hole, how it is formed, ozone layer, CFCs and measures to prevent.
Context: During September and October, the annual ozone hole over the Antarctic reached its peak extent of 16. 4 million sq km on September 8, then shrank to less than 10 million sq km. This has been the smallest observed since 1982. NASA has described it as great news for the Southern Hemisphere.
Why it’s small this year?
There have been abnormal weather patterns in the atmosphere over Antarctica. In warmer temperatures like this year, fewer polar stratospheric clouds form and they don’t persist as long, limiting the ozone-depletion process.
A layer of ozone envelops the Earth and keeps damaging ultraviolet, or UV, radiation from reaching living things on the planet’s surface.
The ozone layer exists mainly in the stratosphere, a layer of the atmosphere that reaches from 10 to 50 kilometers (about 6 to 30 miles) above the Earth’s surface.
What is ozone hole?
The ozone hole is a region of depleted layers of ozone above the Antarctic region, whose creation is linked to increased cases of skin cancer.
Manufactured chemicals deplete the ozone layer. Each spring over Antarctica, atmospheric ozone is destroyed by chemical processes. This creates the ozone hole, which occurs because of special meteorological and chemical conditions that exist in that region.
Factors responsible for the depletion of ozone:
Depletion of ozone is due to many factors, the most dominant of which is the release of chlorine from CFCs (Chlorofluorocarbons) which destroys the ozone. CFCs are released by products such as hairsprays, old refrigerators etc.
Sources: Indian Express.