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June 2007
The first Polar Stratospheric Clouds (PSC) for the year have been detected over Davis, Antarctica, by lidar scientist Didier Monselesan. PSCs promote chemical changes in the atmosphere that lead to the formation of the ozone hole over Antarctica each year. They occur only at high polar latitudes in winter, when temperatures in the stratosphere (8-50 km above ground) fall below about -85ºC.
Average temperatures in the Antarctic lower stratosphere are currently below average. The situation is similar to 2006 when persistently low winter temperatures lead to record levels of ozone destruction.
Although invisible to the eye, the PSCs were revealed by the Davis atmospheric lidar. The lidar uses pulsed light from a powerful laser to map clouds and measure atmospheric temperatures. The PSCs first appeared on May 28 as a thin layer at an altitude of 22 km.
The sloping wavy features in the cloud layer arise from a rising and falling motion due to atmospheric waves propagating up from the lower atmosphere. Based on the prevailing temperatures and characteristics of the lidar measurements, it is likely that the PSCs consisted of micron-diameter particles comprised of an icy mixture of water with nitric acid and sulphuric acid.
A photograph taken on the same evening shows the green laser beam of the lidar, the green arcs of the aurora australis and a waxing gibbous moon.
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| Author: neyha 08 Jul 2008 | Member Level: Diamond | Rating:  Points: 6 |
Interesting information sara 1.Let me tell share with you something that i know about this topic.As we all know CFC is a banned product but does anyone know the reason for it?The answer everyone would promptly give is that they are responsible for the hole in the ozone layer but do you know how?Chloro fluro carbon's known has CFC converts the ozone into oxygen.Conversion of ozone to oxygen also occurs naturally but earlier there was a balance.The rate of formation of Ozone and conversion of ozone was balanced hence the ozone layer was not harmed .Release of CFC has created an unbalance hence the rate of conversion of ozone to oxygen became faster.
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| Author: Ankush Das - Editor 08 Jul 2008 | Member Level: Diamond | Rating: Points: 6 |
The first ozone hole was detected over Antarctica. Scientists are now fearing that because of the greenhouse gases such as methane, nitrous oxide, CFC are destroying the ozone layer and creating a hole which is resulting in the faster melting of the Antarctic ice in addition to the already visible effect of global warming. The nature is surely at great danger. All the harmful UV-B rays are going to reach the earth in a much easier way and will cause skin cancers and cataracts with the exposure to UV-B rays.
LET US PLEDGE THAT WE WILL ALL CONTRIBUTE TO SAVE THE ENVIRONMENT AND HELP IT PRESERVE FOR THE FUTURE GENERATION.
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| Author: Syed 09 Jul 2008 | Member Level: Diamond | Rating: Points: 4 |
Chloroflourocarbons were first created in 1928 as non-toxic, non-flamable refrigerants, and were first produced commercially in the 1930's by DuPont. The first Chlorofluorocarbon was CFC-12, a single carbon with two chlorines and two Fluorines attached to it.
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