Question

Ozone hole over Antarctica appears during
A) Late august- earlyOctober
B) March-April
C) October-November
D) January-February

Answer 1

Hint: Ozone layer is the shield of earth’s stratosphere. It absorbs most of the sun’s ultraviolet radiation. The ozone layer absorbs biologically harmful UV radiation coming from the sun.

Complete answer:
The Antarctic ozone hole is defined as an area of the Antarctic stratosphere. In this area the recent ozone levels has dropped to as low as 33% of their pre 1975 values.The concentration of the ozone in the ozone layer is very small but it is crucial.The ozone depletion is due to the presence of chlorine containing source gases.In the polar vortex over 50% of the lower stratospheric ozone is destroyed during the Antarctic spring. Due to breakdown of the ozone in the stratosphere the unabsorbed and dangerous UV radiation is able to reach the Earth’s surface at a higher intensity.Antarctic spring is also called as polar spring is the period from late august to early October.In this period the strong westerly wind circulate around the Antarctic continent creating a polar vortex.Polar vertex results in the formation of polar stratospheric clouds which trap gases including ozone depleting factors.So the correct answer is late august to early October.

Hence option ‘A’ is the correct answer.

Note:The role of sunlight in ozone depletion is the reason for the greatest depletion of the Antarctic zone during spring. During the spring the sun provides the energy to drive photochemical reactions and melts the polar stratospheric clouds releasing CLO which drives the whole mechanism.