Chlorofluorocarbon gases (CFCs) take six or seven years to move up to the stratosphere and the winds spread them all round the world.Extreme cold, a freezing vortex wind, frozen stratospheric clouds and 6-month darkness over Antarctica all provide ideal conditions for chlorine to break from the CFCs.The chlorine (and bromine) gases destroy the ozone during spring (Sept to Dec) and this is what causes the ozone hole.More detail:Chlorofluorocarbon gases (CFCs) and related halocarbon gases are the main cause of ozone depletion all over the world. CFCs released from Western countries take several years to reach the stratosphere where the ozone layer is. During that time winds spread them all over the world. In the presence of ultraviolet light these gases release chlorine and bromine atoms which destroy some of the ozone in the ozone layer. This is called ozone depletion. The ozone hole is a related but different phenomenon. The hole is Antarctica occurs in the spring (September to December). It begins with this overall ozone thinning, but it is assisted by the presence of polar stratospheric clouds (PS clouds). During the extreme cold of winter, with no sun for six months, polar winds create a vortex which traps and chills the air; the temperature is below -80 Celsius. The ice in these PS clouds provides surfaces for the chemical reactions that destroy the ozone. This needs light to kick-start the reactions.In spring the sun rises above the horizon and provides energy which starts the photochemical reactions. The clouds melt and the trapped compounds (chlorine and chlorine monoxide from the CFCs) are released. Ozone in the lower stratosphere is destroyed and the ozone hole appears.By the end of spring warmer December temperatures break up the vortex and destroy the PS clouds. Sunlight starts creating ozone again and the hole begins to repair.(A similar hole in the Arctic [but smaller because of warmer temperatures] occurs during spring.)
How is Antarctica different from other continents?
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How is Antarctica different from other continents?
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There are no countries on Antarctica and no permanent population. Many countries support scientific research stations on Antarctica. The South Pole is located on the continent of Antarctica. Because Antarctica is a polar region, one with no precipitation, it has no lakes or rivers and is in fact Earths driest continent. Average temperatures in the Antarctic interior get down to -70 degrees Celsius during the winter months and -35 degrees Celsius in the warmer months. The coastal temperatures are much warmer with a range of -15 to -32 Celsius in Winter and -5 to 5 Celsius in Summer. The interior of Antarctica is considered the worlds driest desert because the extreme cold freezes water vapour out of the air. Annual snowfall on the polar plateau is equivalent to less than 5 cm of rain. The Antarctic Treaty governs its use and management. It contains no significant vegetation: it does not rain, it is permanently covered in an ice pack up to 4 Km thick, it has the coldest recorded temperature anywhere in the world (-89.5 C), with katabatic winds reaching to 320 kph. Antarctica is colder and more heavily glaciated than any other continent, and it has no permanent residents, although there is a scientific research station there. A number of nations have made territorial claims on portions of Antarctica, however, there are no countries there, unlike other continents. When you enter Antarctica, there is no Immigration and customs procedure once you have cleared the immigration and customs of the last country you visited en route to the continent. It was the last continent to be discovered and have humans set foot on it. Apart from all that, it is pretty ordinary.
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