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Ozone hole: we explain what the phenomenon of its imminent closure is and how it happens. What is the ozone layer for, how it protects us and what are the causes of its opening and closing.
What is Ozone
Ozone is a molecule with the chemical formula O3. It can be represented by an equilateral triangle where the three oxygen atoms are placed at the three vertices.
This is a particular conformation assumed by the oxygen molecule whenis energized. In simple terms, molecular oxygen (O2) rises in the stratosphere and here, hit by the sun's radiation, it evolves into ozone.
Ozone is of fundamental importance to ensure life on earth because it is able to reject ultraviolet radiation.
Ozone hole and uv rays
Radiation from the ultraviolet field (UV rays) are harmful to humans and to all forms of life because the nitrogenous bases that make up DNA are heterocyclic compounds that have a spontaneous absorption peak at 260 nm, therefore precisely in the ultraviolet range.
The ultraviolet rays generated by the sun can induce genetic mutations. Just think that in the laboratory, to originate GMOs (genetically modified organisms) manipulation with ultraviolet rays is often used.
Photons, a corpuscular element of light, at a wavelength of 260 nm are very charged with energy. This energy, absorbed by the DNA bases, causes great damage to the genetic structure of the cell and induces mutations.
Before the ozone layer developed around our planet, life was not possible precisely because of ultraviolet rays. This is why the first forms of life on Earth developed in water, because water is able to filter ultraviolet radiation.
Theozone holeit allows ultraviolet rays to penetrate which are harmful to human life.
Ozone hole, what it is and causes
Theozone holeit is not to be imagined ONLYlike onechasmor ahole!
With the termozone holereference is made to two phenomena, the first speaks of a thinning of theozone layer, that is, the ozone layer that surrounds and protects the earth.
The ozone layer that surrounds the earth (ozonosphere) is thinner at the equator and thicker at the poles. In the seventies it was discovered that chlorofluorocarbons (CFCs) could cause ozone depletion. In other words, polluting chemical compounds used extensively by man could thin the ozonosphere. This thinning can be more or less marked in the areas of theozone layerin which the thinning is more marked we speak ofozone hole and concerns the polar regions of the earth, in particular the South Pole.
Ozone hole, definition
The ozone hole is a cyclical depletion of the stratospheric ozone layer (ozonosphere) which occurs, mainly in spring, above the polar regions. The decrease can reach up to 71% in Antarctica and 40% (2011) in the Arctic area. The ozone depletion indicates the generic thinning of the ozone layer, a strip of the stratosphere.
Closure of the ozone hole
The phenomenon ofozone holehas been drawing attention to itself since the 1970s.
In 1987, an important agreement limited the use of pollutants capable of causing a thinning in theatmospheric ozone. Today, NASA surveys are registering improvements even if, in 2006, NASA also detected the image of the largest hole in the ozone layer, over the Antarctic, never previously recorded.
Much progress has been made between 2006 and 2017. A study published in Science and signed by the team of researchers from the University of Leeds (UK) and the team from the Massachusetts Institute of Technology (MIT, USA) reports that we are witnessing a timidclosing the ozone hole.
According to the measurements, theozone holein the South Pole it has seen a significant thickening since 2000, shrinking by about 4 million square kilometers. According to the team of researchers, the ozone hole near the South Pole is expected to close completely by 2050.
Thereclosing the ozone holeand the thickening of the layers of the ozone layer at risk, should be the consequence of the Montreal Protocol of 1987: thanks to this agreement, substances consideredcause of the ozone hole. In particular, since 1987 chlorofluorocarbons used in refrigerators and spray cans were banned.
The ozone hole on the South Pole can be taken as a reference for the whole ozonosphere. The South Pole, in fact, is the largest ozone hole in the globe due to the climatic trend typical of this location.
If ozone is good for the planet if it is found in the stratosphere, the ozone released into the earth's atmosphere is highly harmful to human health. For more information on ozone pollution, read the articles: Agricultural water pollution is How to protect yourself from smog.
In the photo, the southern hemisphere ozone hole recorded by NASA over the Antarctic in September 2006. The Antarctic includes the lands and seas surrounding the South Pole. Located in the southern hemisphere.
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