They had been measuring ozone in the Antarctic atmosphere since and had never before seen the levels drop so much. Why would ozone levels have dropped? Could it just be natural variation?
Since ozone concentrations over this region often vary from season to season, the researchers weren't concerned, but record low ozone levels kept occurring nearly every spring. No one knew why. They were the first to find an ozone hole and it would later be identified as the world's largest ozone hole.
An ozone hole is really not a hole but rather a thinning of the ozone layer in the stratosphere that changes seasonally. It wasn't until that scientists were certain that this was a major problem and it was human-caused. The culprits were chemical compounds called chlorofluorocarbons CFCs , which started to be used in the s in air conditioners, aerosol spray cans, and industrial cleaning products.
They were also used to make Styrofoam. And they were capable of breaking apart ozone molecules, causing the breakdown of ozone in the stratosphere to happen faster than it could be built back up. This animation shows the destruction of an ozone molecule by a chlorine atom. Scientists use a unit called the Dobson Unit abbreviated DU to describe the amount of ozone in the atmosphere.
They calculate how thick the ozone layer would be if all ozone in the atmosphere were compressed into a single layer at zero degrees Celsius and sea level atmospheric pressure that is mbar. To get a better understanding, picture a column extending through the ozone layer. That column would capture a certain number of ozone molecules.
However, these ozone molecules would be widely spread out throughout the column. Now let's say that you were to take all the ozone molecules caught within the column and compress them to sea level pressure, and then measure the thickness in millimeters.
Multiply the number by , and you have the thickness of the ozone layer expressed in Dobson Units! The average thickness is about DU, which equals a three millimeter or 0. Yes, the ozone layer is really rather thin!
Just as UV levels vary according to different factors, ozone levels follow a similar course. A distinct ozone pattern exists over the entire globe. There is less ozone over the equator than over other parts of the world, exempting the seasonal ozone hole in Antarctica.
JavaScript appears to be disabled on this computer. Please click here to see any active alerts. Ozone O3 is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth's upper atmosphere the stratosphere and lower atmosphere the troposphere.
Depending on where it is in the atmosphere, ozone affects life on Earth in either good or bad ways. Stratospheric ozone is formed naturally through the interaction of solar ultraviolet UV radiation with molecular oxygen O2.
The "ozone layer," approximately 6 through 30 miles above the Earth's surface, reduces the amount of harmful UV radiation reaching the Earth's surface. Tropospheric or ground-level ozone — what we breathe — is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds VOC and nitrogen oxides NOx.
These reactions have traditionally been viewed as depending upon the presence of heat and sunlight, resulting in higher ambient ozone concentrations in summer months. Within the last decade, however, high ozone concentrations have also been observed under specific circumstances in cold months, where a few high elevation areas in the Western U. Perhaps you are wondering how it is that ozone is able to keep out UVB radiation. Ozone is an unstable and reactive gas.
Because it is so reactive, the ozone in our atmosphere is very dynamic - it is being created and destroyed all the time. When UV light passes through the ozone layer, oxygen molecules are split up into their constituent oxygen atoms. These single atoms are then able to react with other oxygen molecules, forming ozone. This process is an endothermic reaction, meaning it needs to absorb energy in this case the UV radiation in order to occur.
This also happens in reverse - because ozone is so unstable, each ozone molecule soon splits into an oxygen molecule and an oxygen atom.
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