The Ozone Depletion Phenomenon

The ozone layer is one of the oldest things on the planet, older than any of the ancient creatures we see in our museums today. The ozone layer has provided protection for the living components under it for millions of years, and without the ozone layer, we most likely would not be here today. Our evolution would have been cut off millions of years ago without our planet's built in sunscreen.

The Ozone Layer is a layer of ozone particles scattered between 19 and 30 kilometers (12 to 30 miles) up in the earth's atmosphere. The concentration of ozone in the ozone layer is usually under 10 parts ozone per million. Without the ozone layer, UV radiation would not be stopped from entering the earth's atmosphere and coming to the surface.

Like an infection that grows more and more virulent, the continent-size hole in Earth's ozone layer keeps getting bigger and bigger.

Each year since the late 1970s, much of the protective layer of stratospheric ozone above Antarctica has disappeared during September, creating what is popularly known as the ozone hole. The Antarctic hole now measures about 9 million square miles, nearly the size of North America. Less dramatic, but still significant, depletion of ozone levels has been recorded around the globe. With less ozone in the atmosphere, more ultraviolet radiation strikes Earth, causing more skin cancer, eye damage, and possible harm to crops.

Why the Hole is Over Antarctica

Why is the ozone hole over Antarctica? That is one of the first questions that comes to mind when people think about the ozone hole, so here is the answer. During the Antarctic winter, an oval-shaped polar vortex is formed over the south pole area. The vortex brings ozone rich air from above, and ozone poor air is pushed out. The vortex is extremely cold, reaching temperatures of -80 degrees Celsius (-86 degrees Fahrenheit), and these cold conditions help cause large clouds to form in the atmosphere. The clouds in the extreme cold gradually absorb nitrogen oxide, which is stored in crystals of nitric acid inside of the clouds. As the cloud of water and nitric acid starts to grow, it can grow to the point where it covers the entire Antarctic region. When sunlight passes through the cloud, ozone-destroying chlorine and chlorine oxide are formed from the inactive chlorine and nitric acid in the cloud. The chlorine and chlorine oxide can count for up to 70% of the ozone depletion over Antarctica each year.

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