Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970's by a research group from the British Antarctic Survey (BAS) who were monitoring the atmosphere above Antarctica from a research station .The Halley Research Station BAS research stations in the Antarctic.
Rumor has it that when the first measurements were taken in 1985, the drop in ozone levels in the stratosphere were so dramatic that at first the scientists thought their instruments were defective. Replacement instruments were built and flown out. It wasn't until they confirmed the earlier measurements, several months later, that the ozone depletion observed was accepted as genuine.
Evidence that human activities affect the ozone layer has been building up over the last 20 years, ever since scientists first suggested that the release of chlorofluorocarbons (CFCs) into the atmosphere could reduce the amount of ozone over our heads.
The breakdown products (chlorine compounds) of these gases were detected in the stratosphere. When the ozone hole was detected, it was soon linked to this increase in these chlorine compounds. The loss of ozone was not limited to the Antarctic. Around the same time the first firm evidence was produced that there had been an ozone decrease over the heavily populated northern mid-latitudes (30-60N). However, unlike the sudden and near total loss of ozone over Antarctica at certain altitudes, the loss of ozone in mid-latitudes is much less and much slower. Only a few percentage per year.
What Is Ozone And How Is It Formed?.
Ozone (O3 : 3 oxygen atoms) occurs naturally in the atmosphere. The earth's atmosphere is composed of several layers. We live in the "Troposphere" where most of the weather occurs; such as rain, snow and clouds. Above the troposphere is the "Stratosphere"; an important region in which effects such as the Ozone Hole and Global Warming originate.