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Saturday, January 21, 2012 Ozone hole above the Arctic has actually been caused by COLD weather, say scientists after high-altitude aircraft survey The first ozone hole above the North Pole has been aggravated by extraordinarily cold winter temperatures, say scientists. Cooling of the ozone layer enhances the effect of ozone-destroying substances such as chlorofluorocarbons - CFC. A repeated ozone hole above the Arctic is to be expected, say scientists from the KIT Institute of Meteorology and Climate Research. About a year ago, the scientists detected that ozone degradation above the Arctic for the first time reached an extent comparable to that of the ozone hole above the South Pole. At a level of around 13 miles above the ground, 80 per cent of the ozone was lost, potentially exposing people on Earth's surface to harmful ultraviolet-B rays from the sun, which can cause sunburn and skin cancer. According to the study, occurrence of the Arctic ozone hole was mainly due to the extraordinarily cold temperatures in the ozone layer that is located at about 18 km height in the stratosphere, i.e. the second layer of the earth's atmosphere. There, chlorine compounds originating from chlorofluorocarbons and other pollutants are converted chemically at temperatures below -78°C. These chemical conversion products attack the ozone layer and destroy it. If the trend for colder temperatures in the stratosphere observed in the past decades continues, repeated occurrence of an Arctic ozone hole has to be expected. Read More Cooling of the ozone layer enhances the effect of ozone-destroying substances such as chlorofluorocarbons - CFC. A repeated ozone hole above the Arctic is to be expected, say scientists from the KIT Institute of Meteorology and Climate Research. About a year ago, the scientists detected that ozone degradation above the Arctic for the first time reached an extent comparable to that of the ozone hole above the South Pole. At a level of around 13 miles above the ground, 80 per cent of the ozone was lost, potentially exposing people on Earth's surface to harmful ultraviolet-B rays from the sun, which can cause sunburn and skin cancer. According to the study, occurrence of the Arctic ozone hole was mainly due to the extraordinarily cold temperatures in the ozone layer that is located at about 18 km height in the stratosphere, i.e. the second layer of the earth's atmosphere. There, chlorine compounds originating from chlorofluorocarbons and other pollutants are converted chemically at temperatures below -78°C. These chemical conversion products attack the ozone layer and destroy it. If the trend for colder temperatures in the stratosphere observed in the past decades continues, repeated occurrence of an Arctic ozone hole has to be expected. Read More Posted by Lynsey at 5:14 AM Categories: NATURAL DISASTERS
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Ozonska rupa iznad Antarktika dostigla je svoj maksimum za ovu godinu, otkrivajući rupu koja konkurira veličini sjeverne Amerike, otkrivaju znanstvenici. Pokrivajući oko 25 milijuna kvadratnih kilometara, dostigla je svoj godišnji maksimum 14. 09.2011. te je ove godine dosegla veličinu pete najveće ozonske rupe ikada zabilježene. Najveća veličina ozonske rupe bila je zabilježena 2006. godine, pokrivajući 25,7 milijuna kvadratnih kilometara. To je dokumentirano NASA-inim satelitom Aura. Ozonska rupa prvi put je otkrivena krajem 70. godina prošlog vijeka, prvom misijom satelita koji je mogao mjeriti količinu ozona u atmosferi, svemirskim vozilom nazvan POES, kojeg je osmislila NOAA - National Oceanic and Atmospheric Administration ili Nacionalna Agencija za Oceanografiju i Atmosferu. Rupa je kontinuirano rasla tokom 80. i 90. prošlog vijeka, iako se početkom 2000. rast usporio. Usprkos tome znastvenici su uočili velike razlike u rastu iz godine do godine. Na zemljinoj površini ozon je zagađivač, ali u stratosferi on formira zaštitni omotač koji reflektira ultravioletna zračenja natrag u svemir, štiteći nas od tih štetnih UV zračenja. Međunarodna zabrana korištenja oksidirajućih kemikalija kao CFC (klorofluorougljik) pomogla je u gubitku ozonskog omotača. Usprkos tome, spojevi koji uništavaju ozon su još uvijek u stratosferi, gdje se polako razgrađuju. Kao takve, godine s velikom ozonskom rupom povezuju se sa sve hladnijim zimama na Antarktiku i polarnim vjetrovima koji sprečavaju miješanje ozonom bogatog zraka izvan polarne cirkulacije s ozonom osiromašenog zraka unutar anomalije, navode znanstvenici. Ozonska rupa nije kompletno nestajanje ozona kroz cijelu atmosferu već djelomično nestajanje ozona od 14-22. kilometra iznad zemljine površine. Ove godine, po prvi puta, znanstvenici su otkrili trošenje ozona iznad Arktika. Po prvi puta primjećen je značajan gubitak ozona da bi se mogao zabilježiti kao “Arktička ozonska rupa”. Znastvenici su ovo objavili o2.10.2011. godine u časopisu Nature. 27.10.2011. godine, NASA-in NPP satelit je lansiran noseći OMPS (Ozone Mapper Profiler Suite). Od naprednih senzora na OMPS-u očekuje se točnija mjerenja cijele površine ozonske rupe dok istovremeno mjeri kako se koncentracija ozona širi okomito kroz atmosferu.