Huge hole in the ozone layer over the Arctic, because of extreme cold
Huge hole in the ozone layer over the Arctic, because of extreme cold.
A hole with an area five times greater than that of Germany was opened in the ozone layer over the Arctic for the first time equaling the size of the ozone hole over Antarctica, announced on Sunday, scientists.
Caused by exceptionally low temperatures in North Pole, the hole went 15 days over Eastern Europe, Russia and Mongolia, sometimes exposing people to high levels of UV radiation, researchers announced.
Ozone, a molecule composed of three oxygen atoms are formed in the stratosphere, where ultraviolet filter - rays harmful to vegetation and can cause skin cancer or cataracts.
The Earth's natural shield is regularly "attacked" at the poles in winter and spring, partly because of chlorofluorocarbons (CFCs) used by people and aerosol cooling. CFC production is almost nil today, thanks to the Montreal Protocol signed in 1985.
Intense cold remains the main factor in ozone depletion. Under the effect of cold, water vapor and nitric acid molecules condense to form clouds in the lower layers of the stratosphere. These clouds are formed from chlorine or harmful ozone.
The ozone hole is usually higher in Antarctic than the Arctic because the South Pole is much colder. Measurements carried out so far to the North Pole shows that the ozone hole varies and is much more limited than in the southern hemisphere.
Observations made satellite from winter 2010 to spring 2011 showed that the ozone layer was subjected to heavy trials, at an altitude between 15 km and 23 km. Largest decline - 80% - was recorded at altitudes between 18-20 km.
"For the first time, the decrease was sufficient to talk about a hole rightly ozone layer over the Arctic," said the authors of the study, published Monday, the scientific journal Nature.
Guilty of this is a phenomenon known as "polar vortex", a massive cyclone that forms each winter in the Arctic stratosphere and last year, was formed in extremely cold conditions, said Gloria Manney of the Jet Propulsion Laboratory in California.
"Destruction of ozone began in January, then rose to such a point that concentrations of ozone in the polar vortex region were lower than last year," said Gloria Manney.
Very small values were observed "during the 27 days of March and early April, an area of about 2 million kilometers, or nearly five times the size of Germany or California," said the same researcher.
This value is equivalent to that which corresponded to the destruction of the ozone layer over Antarctica in the mid 80s.
In April 2011, the polar vortex has moved over the most densely populated regions of Russia, Mongolia and Eastern Europe for 15 days. Ground measurements showed "unusually high levels" of ultraviolet light, before the vortex to disappear.
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