Question

The formation of ozone hole in the Antarctic region has been a cause of concern. What would be the reason for the formation of this hole?
1. Presence of prominent tropospheric turbulence; and inflow of chlorofluorocarbon.
2. Presence of prominent polar front and stratospheric clouds; and inflow of chlorofluorocarbons
3. Absence of polar front and stratospheric clouds; and inflow of methane and chlorofluorocarbons
4. Increased temperature at polar region due to global warming

Answer 1

Correct Answer - Option 2 : Presence of prominent polar front and stratospheric clouds; and inflow of chlorofluorocarbons

The correct answer is option 2.

• The Earth's atmosphere is continuously stirred over the globe by winds.
• As a result, ozone-depleting gases get mixed throughout the atmosphere, including Antarctica, regardless of where they are emitted.
• The special meteorological conditions in Antarctica cause these gases to be more effective there in depleting ozone compared to anywhere else
• Human emissions of chlorofluorocarbons (CFCs) and halons (bromine-containing gases) have occurred mainly in the Northern Hemisphere.
• About 90% have been released in the latitudes corresponding to Europe, Russia, Japan, and North America.
• Gases such as CFCs and halons, which are insoluble in water and relatively unreactive, are mixed within a year or two throughout the lower atmosphere.
• polar Front: 
  • ​According to this theory, the warm-humid air masses from the tropics meet the dry-cold air masses from the poles and thus a polar front is formed as a surface of discontinuity.
  • Such conditions occur over sub-tropical high, sub-polar low-pressure belts and along the Tropopause.
• The CFCs and halons in this well-mixed air rise from the lower atmosphere into the stratosphere mainly in tropical latitudes. Winds then move this air poleward both north and south from the tropics, so that air throughout the global stratosphere contains nearly equal amounts of chlorine and bromine.
• In the Southern Hemisphere, the South Pole is part of a very large landmass (Antarctica) that is completely surrounded by the ocean.​