Question Video: Identifying the Correct Explanation for the Formation of Ozone Holes over Antarctica during September | Nagwa Question Video: Identifying the Correct Explanation for the Formation of Ozone Holes over Antarctica during September | Nagwa

Question Video: Identifying the Correct Explanation for the Formation of Ozone Holes over Antarctica during September Science • Second Year of Preparatory School

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In September of each year in the Antarctic, the rate of ozone destruction increases. Why does the formation of these Antarctic ozone holes occur during September?

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Video Transcript

In September of each year in the Antarctic, the rate of ozone destruction increases. Why does the formation of these Antarctic ozone holes occur during September? (A) September is springtime in the Antarctic, and a lot of methane gas is created by animals coming out of hibernation. (B) September is springtime in the Antarctic, and sunlight reaches the region. (C) September is summertime in the Antarctic, and the region receives more sunlight. (D) September is fall in the Antarctic, and the fishing season brings many boats that pollute the ice. (E) September is a busy industrial period for Argentina, Australia, and South Africa, and levels of air pollution increase.

The question asks us to identify why ozone holes form over Antarctica during the month of September. Let’s clear some space to think about this question. During the Antarctic winter, much of Antarctica is in darkness for days to months. This is because of the tilt of the Earth’s axis and its position in its orbit around the Sun. Antarctica points away from the Sun during its winter and is in shadow. However, when September arrives, the Earth has moved a bit in its orbit, and now sunlight begins to reach the region. It is springtime in Antarctica.

Let’s have a closer look at what happens here. Incoming ultraviolet radiation from the Sun interacts with chemical pollutants in the air above the Antarctic. The energy from the UV radiation causes chemical reactions to occur, which destroy ozone molecules. As a result, the concentration of ozone begins to decrease. We call thinning of the ozone layer ozone holes. Ozone holes are not really holes, but areas of low or decreased ozone concentration. Now, we mustn’t get confused. UV radiation from the Sun reaches much of the atmosphere year-round. And chemical pollutants, which are harmful to the ozone layer, exist throughout the atmosphere, not just above Antarctica.

So, why then do ozone holes form over the Antarctic specifically? Well, it is not just the combination of UV radiation and chemical pollutants, which destroy ozone. It is, in fact, the unique combination of UV radiation, chemical pollutants, as well as the low cloud cover and very cold temperatures above the Antarctic, which create the conditions which cause a high rate of ozone destruction.

Now we know how ozone holes form, let’s bring back the answers. Why do ozone holes form in September above the Antarctic? The answer is (B): September is springtime in the Antarctic, and sunlight reaches the region.

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