measure the density of the ozone layer: In 2020, it will be 35 years since we began to listen to talk about a hole in the ozone layer . During this period, humanity was able to do the best, but also the worst. We managed to ban chlorofluorocarbons that killed him in record time, we managed to reverse the process, and soon after that we managed to lose weight.
If the ozone layer has become one of the themes of the end of the century and remains the actual topic of the environmental press today, doubts still remain. I doubt how, for example, How can we know that this damn hole exists?
How do we know that there is a hole in the ozone layer?
The short answer is simple: measure it. What happens is that it is not intuitive, because atmospheric ozone is not visible to the naked eye. Scientists had to answer a vital question to detect the presence of the ozone layer in the atmosphere. Why don’t we get the full spectrum of sunlight? Or, in other words, where is all this ultraviolet light that we should be there, but it does not reach us?
In 1879, the French astronomer Alfred Cornu suggested that the limitation of the ultraviolet tip of the solar spectrum obtained on Earth could only be related to something in the atmosphere. We did not know that this could be, but, having spent many hours studying the measurements, he came to the conclusion that something must block these frequencies from the visible spectrum.
A year later, one of the fathers of spectroscopy, Walter Noel Hartley, who had just assessed the ozone absorption band, found that the estimates were correlated and bound to the gas, possibly for the first time, to an ultraviolet block. So we began to measure ozone , with ultraviolet detectors.
But only in 1912 and 1913, astronomers were able to make the puzzle and suggest that the atmospheric ozone layer was 0, 5 cm thick. From that moment began a long technical career, allowing not only to measure the ozone, but also to understand the functioning of the atmosphere ,
Another key tool during these years was balloon probes (in some cases special aircraft). These pots can carry tools at an altitude of more than 30 km and take air samples in the stratosphere, which are analyzed through a concentration battery. This device is an electrochemical cell that uses potassium iodide and, when in contact with ozone, creates a current to estimate the concentration.
Sometimes these types of balloons may explode (which is why they have built-in parachutes), but these are very useful tools for studying a very illogical layer of the atmosphere. This is Dobson (the one who gave his name to atmospheric ozone units), who realized that, contrary to what we thought, the air temperature does not always decrease with height ,
Based on our historical experience, we thought that the higher you rose, the colder it was. But Dobson noticed that the temperature rises again after the tropopause (the transition zone between the troposphere and the stratosphere). In fact, according to some experts, it can reach 17 degrees (against -55 in the upper troposphere). It was a very clear example of how ozone, which existed in this region of the atmosphere, scattered ultraviolet radiation and heated the environment (what we use today to measure ozone from satellites since Toms already disappear
In 1987, chlorofluorocarbons (CFCs) were banned at the Montreal conference, which I consider to be one of the most successful international efforts in the history of environmental protection. If we didn’t do anything, the hole would be 40% larger than in 2008 and this would have left 25 million square kilometers under the influence of the ultraviolet light of the sun.
But we did it, and just when we were able to say that the ozone layer is being restored, problems arose with countries such as China, bypassing international rules for the bullfighter. It can be seen that much remains to be done, but thanks to monitoring, we know what is happening ,