Ozone hole, a worrying phenomenon concerning that layer of natural gas, ozone, in fact, which protects the Earth from harmful ultraviolet radiation and UV-B rays from the sun. We speak of a "hole" because for several decades this enveloping intangible but precious cover has been increasingly thin and this has happened above all due to the chemicals produced by human activities.
Recent studies, from 2014, carried out byUNEP and from World Meteorological Organization, would argue that after an abundant thirty years of deterioration, the ozone hole is improving, that is, it is shrinking. Is the 1994 Montreal Protocol beginning to have some effect?
Important steps had been taken to ensure that it ozone layer did not disappear more every year, however, it is necessary not to claim victory for this turnaround, but to continue severely reducing the emission of chlorofluorocarbons.
The September 16 is World Ozone Protection Day and it is an opportunity to remind us what to do in the small and large, because although located very far from the ground, the Ozone Hole touches us closely.
Ozone hole: what it is
What we call the ozone hole is not a hole, but the marked and evident thinning effect observable for the ozonosphere, an ozone layer that constitutes a fundamental screen. Its valuable function consists in intercepting radiation that is lethal to life on earth. As things turn around us, ozone is formed mainly in the stratosphere in the tropical latitudes that are more radiated, but then accumulates at high latitudes and at the poles.
The Ozone hole is connected to another phenomenon - the reduction of the ozone layer is and both are linked to the reduction of stratospheric ozone. The ozone depletion occurs slowly and globally, since the early 1980s, while the ozone hole is intermittent but much more powerful and affects the polar regions of the earth.
In both cases, it must be point your finger at halogens, first of all chlorine and bromine, which catalyze ozone-destructive reactions, and on us humans who produce them. Before continuing, a doubt must be resolved that many arise when hearing about ozone as a good gas. As often happens in life, the line between good and bad is not so clear. It depends. In the case of our gas, high altitude is essential to maintaining life on Earth while at low altitude it is highly poisonous.For further information: ozone hole, what it is.
Ozone hole: causes
The Ozone hole it is created and expands when the halogenated compounds of anthropogenic sources reach the stratosphere, triggering the catalytic destruction and thinning the O3 layer that acts as ultraviolet radiation filter by absorbing their UV-C component at 100% and UV-B at 90%. We should not think of an on / off phenomenon, there are in fact some factors that affect the possible enlargement of the ozone hole, let's see the main ones.
There are two equal merits, the quantity of halogenated organic compounds and the quantity of solar radiation. Let's see better: in the case of halogenated organic compounds, that is alkyl halides including chloro-fluoro carbides (CFCs), they are important because they are what react with ozone, their quantity varies with the polar temperature. If colder polar eddies form in winter than in the previous year, the Ozone hole widens.
In the case of solar radiation, we mean the quantity that reaches the polar stratosphere in spring, the more abundant it is, the more ozone decreases. In general al South Pole the vortex is colder and more intense, so the ozone hole is wider. Another factor to which I mention, is that linked to volcanic eruptions which are related to the increase in the hole.
Ozone hole: where it is located
The Ozone hole it is evident mainly in spring and above the polar areas, reaching up to 71% in Antarctica and 40% in the Arctic area. To baptize this creepy phenomenon, "ozone hole”, Was the Nobel Prize Sherwood Rowland, referring to an observed thinning of the ozone layer in the stratosphere at a distance between 10 and 40 kilometers from the earth's surface. At least 30 years ago, this term appeared, which has never stopped being mentioned, indeed.
Ozone hole and the greenhouse effect
Often they are found side by side, but they are two different phenomena even if both caused by changes in the atmosphere caused by human activity.
Furthermore, the greenhouse effect is not in itself a problem, in truth it is a completely natural and useful process because it ensures warming of the earth, without it, the Earth's temperature could be 30 ° C colder. When we talk about greenhouse gases we mean gases present in the atmosphere such as carbon dioxide, ozone, nitrogen peroxide, water vapor and methane.
If we find ourselves having to talk about the'Greenhouse effect as a problem, it is our fault, not the gases: our laborious and somewhat reckless activities have led over the years to an increase in greenhouse gases and a consequent exaggerated global warming.
World Ozone Protection Day
THE September 16 to focus attention on the importance of safeguarding the ozone layer, the World day for the preservation of the ozone layer. It has existed since 1994, the United Nations General Assembly thought of dedicating a date to the Ozone Hole and took advantage of the one in which the Montreal Protocol, important document signed in 1987 by the international community and which also catalogs the chemicals "guilty" of depleting the ozone layer regulating the interruption of production and consumption.
Last year the World day for the preservation of the ozone layer as a slogan "Ozone: everything between you and UV rays". Why should we be so interested in celebrating this date? Because if the ozone layer does not absorb radiation as it should, this has unwelcome effects. Everyone pays the price: microorganisms, animals, plants and even plastics.
As far as we are concerned, the ozone hole can get us for example damage to the eyes and the immune system, skin tumors and accelerated photoaging. Even selfishly, the September 16 it is better to think and inform ourselves, to then do our part.
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