A massive hole in the earth's ozone layer has appeared over the Arctic this spring. Five times the size of California, the hole matches the size of the ozone loss over Antartica, researchers said.

The ozone, made up of molecules of oxygen, forms in the earth's stratosphere. It functions as a filter against the sun's ultraviolet rays that can damage life on earth, including vegetation and animals. Harmful ultraviolet rays can cause skin cancer and cataracts in people, The Australian report explained.

During winter and spring, the ozone layer in both the Arctic region and Antarctica, comes under attack, mainly from extreme cold. This cold temperature causes water vapour and molecules of nitric acid to condense into clouds in the lower stratosphere. In these clouds atmospheric chlorine molecules become reactive compounds that eat the ozone layer.

Traditionally, the ozone hole in the Antarctic is larger than the Arctic because it is colder in the South pole. Arctic records have - until now - suggested that the loss, while variable, is far more limited.

According to 2010-2011 satellite measurements, the Arctic winter-spring ozone was dwindling at a height between 15 and 23 kilometers. A loss between 18 and 20 kilometers was considered the biggest so far.

"For the first time, sufficient loss occurred to reasonably be described as an Arctic ozone hole," said a study, which appeared in the British science journal "Nature."

The polar vortex, a large-scale cyclone that forms every winter in the Arctic stratosphere, was formed last winter under extremely cold conditions, explains Gloria Manney, of the Jet Propulsion Laboratory in California.

"The ozone destruction began in January, then accelerated in late February and March, so that ozone values in the polar vortex region were much lower than usual from early March through late April, after which the polar vortex dissipated.

"Especially low total column ozone values (below 250 Dobson Units) were observed for about 27 days in March and early April.

"The maximum area with values below 250 Dobson Units was about two million square kilometres, roughly five times the area of Germany or California."

An ozone loss of similar magnitude was said to have occurred in the Antarctica in the mid-1980s.

Shifting Hole

Researchers have also found out that in April that for about two weeks the vortex shifted locations over more densely populated parts of Russia, eastern Europe, and Mongolia.

Ultra-violet measurements on the ground indicate "unusually high values." Fortunately, human exposure was not constant, because the vortex shifted positions every day before fading, stated Manney.

"The study, published by the journal, Nature, challenges conventional thinking about the Arctic's susceptibility to ozone holes. This thinking is based on only a few decades of satellite observations," continues The Australian.

"The Arctic stratosphere continues to be vulnerable to ozone destruction caused by ozone-depleting substances linked to human activities," said World Meteorological Organization (WMO)Secretary-General Michel Jarraud. "The degree of ozone loss experienced in any particular winter depends on the meteorological conditions. The 2011 ozone loss shows that we have to remain vigilant and keep a close eye on the situation in the Arctic in the coming years," he said in theozonehole.com site.