Ozone is formed from dioxygen by the action of ultraviolet light uv and electrical discharges within the. In the simplest approach to ozone mitigation based on voc controls, emission reductions are implemented on a mass basis without any regard to the unique chemistry of each. Unusual winds drive a small 2019 ozone hole youtube. Stratospheric ozone depletion, ultraviolet radiation and health. Nov 04, 2012 the ozone molecules o3 are highly active state and once they come into contact with contamination in the air, like microorganisms, germs bacteria, virus, poisonous gas, odors etc. National aeronautics and the ozone hole space administratio n. In this time, we have not witnessed an ozone hole formation of this size over the arctic. The measurements were made with groundbased dobson spectrophotometers see box in q5. It traces the history of the ozone hole from the stage of formation of the stratospheric ozone layer, millions of years ago, into the late 20th century when. This timeline highlights the average area of the ozone hole between september 7th and october th as observed by nasa spacedbased instruments see.
Free oxygen atoms can recombine to form oxygen molecules but if a free oxygen atom collides with an oxygen molecule, it joins up, forming ozone. There are many causes for ozone depletion, but the most important process in both trends is catalytic destruction of ozone by atomic chlorine and. The ozone hole and global warming union of concerned scientists. Cfcs in order to protect the ozone in the stratosphere. In the beginning, the protocol addressed the production and consumption of primarily cfcs. Thanks to the ozone layer, life on earth was made possible. It is produced at ground level through a reaction between sunlight and, e. The ozone layer protects life on earth from harmful solar ultraviolet uv radiation. Overall, the 2014 ozone hole is smaller than the large holes of the 19982006 period, and is comparable to 2010, 2012, and 20. Pdf ozone in the stratosphere is constantly being produced and destroyed by. Later it was found that certain specific set of conditions were responsible for the formation of the hole. In a mini hole, ozone is not destroyed as it is in the antarctic ozone hole. Ozone is formed in the atmosphere when energetic ultraviolet uv radiation dissociates molecules of oxygen, o 2, into separate oxygen atoms. Marusek 24 february 2005 introduction the earth is surrounded by a thin layer of ozone in the middle atmosphere stratosphere about 25 kilometers above the earths surface.
The ozone hole in antarctica cool antarctica, pictures. The largest singleday ozone hole ever recorded by satellite was 29. The ozone hole has steadily grown in size and length of existence over the past two and half decades. Antara banerjee and her colleagues at the university of colorado boulder did the research and noted that the ozone layer in the northern hemisphere is on track to fully recover to its 1980s levels sometime in the 2030s. The ozone molecule is very unstable and has a short halflive, causing it to fall back into its original form after a while, according to the following reaction mechanism. Ozone has proven to be among the most difficult air pollutants to control. It is formed of three oxygen atoms giving it the chemical formula, o3.
Ozone only returns to normal values after the vortex is broken up and midlatitude air is able to enter the sky over antarctica replenishing ozone and converting the active chlorine back to an inactive form. Ozone hole poster back the back of the poster provides information about stratospheric ozone. The emission of ozonedepleting gases impacted the earths ozone layer a layer that. The ozone hole in antarctica the seasonal thinning of the ozone layer of the earths atmosphere above antarctica, so allowing abnormal amounts of ultraviolet light to reach the earths surface in those regions. Click any map image to bring up a new page with a highresolution image. Satellite measurements then confirmed that the springtime ozone loss was a continentwide feature.
Ozone depletion consists of two related events observed since the late 1970s. The ozone layer formed slowly over billions of years. People, plants, and animals living under the ozone hole are harmed by the solar radiation now reaching the earths surfacewhere it causes health problems, from eye damage to skin. This is why ozone holes first formed, and are deeper, over antarctica. Much larger decrease in stratospheric ozone is observed around earths polar regions. In 1985, an extreme depletion of ozone over antarctica was discoveredthe socalled antarctic ozone hole. The production of ozone near the surface does not significantly contribute to the abundance of stratospheric ozone.
One important effect is that ozone depletion in the stratosphere increases the formation of photochemical smog, including ozone accumulation, in the lower troposphere. The concept of ozone forming potential and its quantification in any given airshed, it is common to find hundreds of different voc species, each with its own unique chemistry. Free oxygen atoms can recombine to form oxygen molecules but if a free oxygen atom collides with an oxygen molecule, it joins. Ozone hole in some of the popular news media, as well as in many books, the term ozone hole has and often still is used far too loosely. Ozone is a minor constituent of the stratosphere 110 ppm. The ozone hole is defined geographically as the area wherein the total ozone amount is less than 220 dobson units. Some scientists are seeing the beginnings of a decline in the amount of cfcs in our atmosphere which may, may not mean the ozone hole will recover sometime in the future.
This drives strong cooling of the lower stratosphere and creates the conditions favourable for psc formation. Ozone is also present in the troposphere formed mainly by the action of sunlight on pollution from motor vehicles here it helps to form photochemical smog and is a pollutant. Ozone hole is the area of the earths atmosphere where abnormal reductions of ozone occur, it is an annual phenomenon observed during the spring in the polar regions and is usually followed by a recovery during the summer. Jan 20, 2010 this yearly occurrence is called the ozone hole. On wednesday, a research paper released in science daily showed that the ozone layer has started recovery due to changing wind patterns. It is thought by many to be caused by our use of fossil fuels such as oil, gas and coal. Tthe ozone hole and global he ozone hole and global wwarming 1arming 1 the ozone hole and global warming global warming global warming is an increase in the average temperature of the earths atmosphere, leading to climate change. Ozone is a strong oxidant which attacks electron rich structures in molecules, such as double bonds removes up to 99% paired with h 2 o 2 reduces treatment time and reaction tank volume required due to formation of hydroxyl radicals and secondary oxidants removal of pharmaceuticals. In the above diagram, oxygen atoms are represented as dark blue circles. This video demonstrates how oxygen gas in the atmosphere becomes ozone and how ozone protects us from ultraviolet radiation. View the latest status of the ozone layer over the antarctic, with a focus on the ozone hole. May 25,2000upper atmospheric conditions in the northern hemisphere are becoming similar to those of the antarctic.
What is an ozone hole and causes and effects of ozone. Ozone hole ozone depletion at south pole polar vortex and ozone depletion are two distinct but related phenomena. Jun 02, 2014 polar vertexcold circulating wind, formation of stratospheric clouds and 6 months of darkness over antarctic, all provide ideal conditions for chlorine to break from the cfcs. Why is it important that the destruction process be. How the ozone hole forms the ozone hole is not really a hole but a thinning of the ozone layer over the south polar region. The data were acquired by the ozone monitoring instrument on nasas aura satellite. Fossil fuel combustion is a primary source of pollutant gases that lead to tropospheric ozone production. The origin of the ozone hole natural or anthropological james a. Causes of ozone layer depletion and its effects on human. There is a steady decline of about 4% in the total volume of ozone in earths stratosphere. Ozone formation and destruction cooperative institute for. Stratospheric ozone o3 is produced by the combination of an oxygen atom o with an oxygen molecule o2.
The result of this could be the formation of an arctic ozone hole or low ozone event. The hypothesis on the formation of the ozone hole due to the action of some molecules emitted by the rockets has been suggested. Additionally, a timeline highlights the average area of the ozone hole and the emissions rates of humanproduced ozone depleting substances odss. The term ozone hole refers to a phenomenon observed yearly over the south. To control ozone requires understanding its complex chemistry and how the chemical travels from one locality to another. That is, ozone depletion in the upper atmosphere will allow more ultraviolet radi.
Ozone layer introduction the ozone layer refers to the ozone within stratosphere, where over 90% of the earths ozone resides. In the measurements made in recent times significant reductions in ozone concentrations in the layer, with special. Apr 23, 2020 view the latest status of the ozone layer over the antarctic, with a focus on the ozone hole. Atmosphere human presence remote sensing world of change videos. Tthe ozone hole and global he ozone hole and global global. This visualization is a plot of an isosurface of ozone volume mixing ratio at 5 x 107 parts per million. This timeline highlights the average area of the ozone hole between september 7th and october th as observed by nasa spacedbased instruments see colored bars and scale. The ozone hole is the region over antarctica with total ozone of 220 dobson units or lower. Ozone is an irritating, corrosive, colorless gas with a smell something like burning electrical wiring. Nasa ozone watch images, data, and information for atmospheric ozone ozone maps. Pdf causes of ozone layer depletion and its effects on. It is a pale blue gas with a distinctively pungent smell. Watch how ozone concentrations in the stratosphere have changed from 1979 through 2018. Sep 30, 2014 ozone is a colorless gas mainly found in earths stratosphere.
It is an allotrope of oxygen that is much less stable than the diatomic allotrope o 2, breaking down in the lower atmosphere to o 2. Oct 23, 2019 the unexpected discovery of a hole in the atmospheric ozone layer over the antarctic revolutionized science and helped to establish one of the most successful global environmental policies of. Ozone depletion, gradual thinning of earth s ozone layer in the upper atmosphere caused by the release of chemical compounds containing gaseous chlorine or bromine from industry and other human activities. Claus zehner, esas copernicus sentinel5p mission manager, adds, the tropomi total ozone measurements are extending europes capability of the continuous global ozone monitoring from space since 1995. Ozone is a photochemical product of oxygen which is formed by solar radiation of short wave length. The upper layer of the atmosphere enveloped by ozone 15 to 30 km is known as ozone layer or ozonosphere. The ozone layer is repairing itself, affecting wind. Now, the size of ozone hole over antarctica is estimated to be about 30 million sq.
Ozone also occurs in very small amounts in the troposphere. Chlorofluorocarbons ozone depletion occurs when the natural balance between the production and destruction of stratospheric ozone is disturbed. Good ozone is good only because it is in the stratosphere where we cannot breathe it see figure below. The antarctic ozone hole is an area of the antarctic stratosphere in which the recent since about 1975 ozone levels have dropped to as low as 33% of their pre1975 values. The latter phenomenon is referred to as the ozone hole. Understanding the ozone hole powerpoint followsheet. From 6 august onwards, the ozone hole can be seen forming in an area south of south america around the polar night. Ozone is a gas found in the atmosphere consisting of three oxygen atoms. The ozone depletion process the discovery of the antarctic ozone hole the first decreases in antarctic total ozone were observed in the early 1980s over research stations located on the antarctic continent. Jun 07, 2017 ozone layer and its depletion animation mcgrawhill animations. Stratospheric ozone depletion has further indirect health effects. Jan 07, 2016 ozone hole ozone depletion at south pole polar vortex and ozone depletion are two distinct but related phenomena.
In the late 20th century, human emissions of chemical substances called halocarbons adversely affected the amount of ozone molecules in the atmosphere, most notably resulting in the dramatic annual ozone hole. Formation of ozone ozone, uv and aerosol studies rmi. Bad ozone also absorbs solar ultraviolet light, but it is down near earths surface where we can breathe it. Ozone filters out uv light from reaching the surface of the earth and. Mechanism of ozone formation and ultraviolet absorption. So, while ozone is continually being replenished, it is also continually being destroyed. The concept of ozoneforming potential and its quantification. An ozone mini hole is a localized and transient reduction in total ozone column amounts, usually found from the midlatitudes into the polar regions. Before the ozone layer had been formed, the solar shower of uv radiation reaching the earth was so strong that no life was possible on earth.
Ozone normally forms a protective blanket in the stratosphere, about 10 to 50 kilometres above the ground, where it shields life from solar ultraviolet radiation. As a pollutant it should not be confused with the separate problem of stratospheric ozone depletion. Abnormal weather patterns in the upper atmosphere over antarctica dramatically limited ozone depletion in september and october, resulting in the smallest ozone hole observed since 1982, nasa and noaa scientists reported today. The term ozone hole refers to the depletion of the protective ozone layer in the upper atmosphere stratosphere over earths polar regions. Stratospheric ozone production earth system research. Ozone in the stratospherea layer of the atmosphere between 15 and 50. Ozone layer and the formation of the ozone hole aa. This active chlorine, bromine and other ozone depleting substances destroys the ozone 1% per day during spring causing the formation of ozone hole. The thinning of the ozone layer is caused by a chemical reaction where man.
The buildup of oxygen in the atmosphere led to the. Ozone is a molecule that consists of three negatively charged oxygen atoms. The 2017 antarctic ozone hole summary department of the. Stratospheric ozone is formed naturally by chemical reactions involving solar ultraviolet radiation sunlight and oxygen molecules, which make up. After thinning at alarming rates in the 1980s and 90s, the ozone layer over antarctica is starting to recover. Basic mechanisms and photooxidant air pollutionphotooxidant air pollution. It forms a protective layer that absorbs harmful ultraviolet light from the sun. This book underscores the reemergence of the ozone hole problem and deals with it in its current context of exacerbating global warming.
Jh st hlijohannes staehelin institute for atmospheric and climate science c, s ss ede a st tute oiaceth, swiss federal institute of technology zurich ethz universitatstrasse 16 ch8092 zu i h s it l d8092 zurich, switzerland. The antarctic ozone hole was discovered by the british antarctic survey from data obtained with a groundbased instrument from a measuring station at halley bay, antarctica, in the 19811983 period. The ozone hole over 30 years of nasa observations aura. Ozone hole is the smallest on record since its discovery. What are the mechanisms that chapman missed to destroy ozone. Every year, since at least 1978, there is a sudden, rapid decrease in the stratospheric ozone levels at the end of the antarctic winter. Satellite instruments monitor the ozone layer, and we use their data to create the images that depict the amount of ozone.