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The Ozone Layer is the portion of the atmosphere that contains high levels of the oxygen molecule ozone. This molecule plays an important role acting as a natural UV shield for the Earth. You may wonder where is the ozone layer located to play such a vital role so effectively. The Ozone layer is actually located in the stratosphere in a region that is 10 to 50 km above the Earth.
So why is the Ozone layer so important? As mention before the secret lies in oxygen molecules. Normal oxygen in its natural molecular state is made up of only two atoms. However this changes when oxygen in the thermosphere is exposed the Sun’s ultraviolet rays. The rays separate oxygen molecules the free oxygen joins with the remaining two atom oxygen molecules to create ozone. This process might seem simple but it helps to screen out 99.5 percent of the ultraviolet radiation that the Sun sends towards earth. The times that the ozone layer didn’t screen out this type of radiation at such levels life was almost wiped out according to the geologic record.
You might think that this is an exaggeration until you observe the biological damage UV rays can do. We have already seen the harm caused when people don’t take the proper precautions when going to the beach. The least harm comes in the form of sun burn. People overexposed to the UV rays that do make it to earth have their skin damaged by the UV energy that penetrates their skin. However it gets more serious the longer a person is exposed to UV rays. The reason is because the damage gets to the cellular level causing cancers and genetic damage. Essentially it’s like being exposed to a nuclear reactor in melt down. The high energy radiation over time would accumulate harm in living tissue until it killed the organism exposed to it.
Despite its importance industry produced and released chemicals into the air that interfered with the ozone cycle. The main problem chemical CFC’s prevented oxygen molecules from complete the bonding process that is important for the completion of the ozone cycle this caused a major depletion of ozone in key areas of the Earth’s atmosphere. This is huge when the natural concentration of ozone was already quite low. This just goes to show the delicate balance that was upset. Fortunately nations upon hearing the harm caused started bans on CFC’s while industry tried to find alternatives to use in products. The result started to show with ozone depletion actually slowing down and reversing with scientist predicting recovery within the next century.
We have written many articles about the ozone layer for Universe Today. Here’s an article about the depletion of the ozone layer, and here’s an article about the ozone layer.
If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.
We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.