21. Stratospheric Ozone Depletion NASA resource file for students and teachersCategory Science Environment Global Change ozone layer...... http://www.nas.nasa.gov/Services/Education/Resources/TeacherWork/Ozone/Ozone.hom

Stratospheric Ozone Depletion This page has been moved to: http://www.nas.nasa.gov/About/Education/Ozone/ Please update your bookmark. Curator: Jill Dunbar Last Update: July 5, 2002 NASA Official: Walt Brooks

22. The Ozone Hole Tour : Home Page An overview of the ozone layer and the development of the ozone hole over the Antarctic hosted by the Centre of Atmospheric Science, University of Cambridge. http://www.atm.ch.cam.ac.uk/tour/index.html

Centre for Atmospheric Science Notes for teachers Visited over 3500 times a week! Awards and citations for the Ozone Hole Tour deutsch Before You Start! I: The Discovery of the Ozone Hole II: Recent Ozone Loss over Antarctica III: The Science of the Ozone Hole IV: Latest Ozone Hole Research at Cambridge Glossary Credits More Info ... Centre for Atmospheric Science , Cambridge University, UK. No text or graphics can be used or reproduced without explicit written permission. This version designed and maintained by Dr. Glenn Carver . Original concept and design Owen Garrett. French translation by , German translation by Dr. Olaf Morgenstern

23. Ozone Layer Similar pages More results from www.nas.nasa.gov Ozone depletionKey textKey text Earth's sunscreen – the ozone layer, Published by Sponsored by telstra.com.The ozone layer screens out the sun’s harmful ultraviolet radiation. http://www.nas.nasa.gov/Services/Education/Resources/TeacherWork/Ozone/Ozone.lay

The Ozone Layer "The ozone layer" refers to the ozone within stratosphere, where over 90% of the earth's ozone resides. Ozone is an irritating, corrosive, colorless gas with a smell something like burning electrical wiring. In fact, ozone is easily produced by any high-voltage electrical arc (spark plugs, Van de Graaff generators, Tesla coils, arc welders). Each molecule of ozone has three oxygen atoms and is produced when oxygen molecules (O2) are broken up by energetic electrons or high energy radiation. For information on the history of the ozone layer for the layman, see the Short history of ozone depletion , National Oceanic and Atmospheric Administration's NOAA Ozone overview or NOAA on stratospheric ozone . For short and to-the-point answers, check out Robert Parson's Ozone overview, FAQ1 The Stratosphere Variations in temperature and pressure divide the earths atmosphere into layers, shown below, and mixing of gases between the layers happens very slowly. The altitudes on the diagram are logarithmic so an analogy in the glossary might give you a better idea of the relative thicknesses of these layers.

24. Öko-Recherche Analyses of material flows of chemicals in the environment, including chemicals damaging the ozone layer. http://www.oekorecherche.de/english.html

25. EUROPA - Environment - Ozone Layer Protection Homepage Important legal notices. en, EUROPA European Commission Environment Policies Climate Change ozone layer Protection, Contact Search on EUROPA. http://europa.eu.int/comm/environment/ozone/

en EUROPA European Commission Environment Policies ... CONTACT US last update: E-mail this page Glossary Site Map Index ... Top

26. The Ozone Secretariat, UNEP - Homepage Intergovernmental organization for the Vienna Convention for the Protection of the ozone layer and the Montreal Protocol on Substances that Deplete the ozone layer. Includes information on these treaties and their implementation. http://www.unep.org/ozone/index-en.shtml

Français Español English Nairobi, Sunday March 23 2003 About The Secretariat Ozone Treaties Status of Ratification Reports and Documents ... Contact Addresses Highlights Synthesis of the 2002 Assessments of the Assessment Panels of the Montreal Protocol The 2002 Assessment of the Science Assessment Panel The 2002 Assessment of the Environmental Effects Assessment Panel The 2002 Assessments of the TEAP and its TOCs ... Contact Webmaster - OzoneInfo@unep.org

27. EUROPA - Environment - The Ozone Layer The ozone layer. This ozone layer performs the essential task of filtering outmost of the sun's biologically harmful ultraviolet (UVB) radiation. http://europa.eu.int/comm/environment/ozone/ozone_layer.htm

en EUROPA European Commission Environment Policies ... Developments The Ozone Layer Although ozone (O ) is present in small concentrations throughout the atmosphere, most ozone (about 90%) exists in the stratosphere, in a layer between 10 and 50km above the surface of the earth. This ozone layer performs the essential task of filtering out most of the sun's biologically harmful ultraviolet (UV-B) radiation. Concentrations of ozone in the atmosphere vary naturally according to temperature, weather, latitude and altitude. Furthermore, aerosols and other particles ejected by natural events such as volcanic eruptions can have measurable impacts on ozone levels. The Ozone Hole In 1985, scientists identified a thinning of the ozone layer over the Antarctic during the spring months which became known as the "ozone hole". The scientific evidence shows that human-made chemicals are responsible for the creation of the Antarctic ozone hole and are also likely to play a role in global ozone losses. Ozone Depleting Substances (ODS) have been used in many products which take advantage of their physical properties (e.g. chlorofluorocarbons (CFCs) have been used as aerosol propellants and refrigerants). CFCs are broken down by sunlight in the stratosphere, producing halogen (e.g. chlorine) atoms, which subsequently destroy ozone through a complex catalytic cycle. Ozone destruction is greatest at the South pole where very low stratospheric temperatures in winter create polar stratospheric clouds (PSCs). Ice crystals formed in PSCs provide a large surface area for chemical reactions, accelerating catalytic cycles. The destruction of ozone also involves sunlight, so the process intensifies during spring time, when the levels of solar radiation at the pole are highest, and PSC's are continually present.

28. Page Under Construction wcnareasm.gif, Click the image for more details of the changes of the Antarcticozone layer over the last twenty years. Webmaster renaudot_c@gateway.wmo.ch. http://www.wmo.ch/web/arep/ozone.html

Global Atmosphere Watch WMO Home AREP Home GAW home MEETINGS ... EXTERNAL LINKS OZONE BULLETINS AND DATA WMO Antarctic Ozone Bulletins: WMO Northern Hemisphere: Ozone data including maps Other sources of information: Global: Scientific Assessment of Ozone Depletion: 2002 Executive Summary [Background information Ozone Maps (MSC Canada) TOVS satellite images (NOAA USA) Total Ozone Mapping Spectrometer (NASA USA) 50hPa temperature analysis (NOAA USA) Antarctic WMO Press Release Antartic Ozone Hole Splits In Two Background Information NILU Norway Ozone and temperature crossections (Neumayer station (AWI-Germany)) South Pole sounding (NOAA USA) Animation of the Ozone Hole at the South Pole (NOAA USA) Click the image for more details of the changes of the Antarctic ozone layer over the last twenty years Webmaster: renaudot_c@gateway.wmo.ch

29. Ozone Layer Burned By Cosmic Rays ozone layer Burned by Cosmic Rays. Cosmic rays may be enlarging the hole in the ozonelayer, according to a study appearing in the 13 August print issue of PRL. http://focus.aps.org/story/v8/st8

Previous Story Next Story July - December 2001 Archive Phys. Rev. Lett. (print issue of 13 August 2001) 2 August 2001 Title and Authors Ozone Layer Burned by Cosmic Rays NASA TOMS satellite Cosmic conspiracy. Cosmic rays could be a major contributor to ozone destruction over Antarctica. Cosmic rays may be enlarging the hole in the ozone layer, according to a study appearing in the 13 August print issue of PRL . Researchers analyzed data from several sources, and found a strong correlation between cosmic ray intensity and ozone depletion. Back in the lab they demonstrated a mechanism by which cosmic rays could cause a buildup of ozone-depleting chlorine inside polar clouds. Their results suggest that the damage done by cosmic rays could be millions of times larger than anyone previous believed and may force atmospheric scientists to reexamine their models of the antarctic ozone hole. For the past two decades, scientists have known that human-made chlorofluorocarbons (CFCs) are the major destroyers of the atmosphere's protective ozone layer. Atmospheric scientists have proposed that ultraviolet light breaks down CFCs, releasing active chlorine, which tears apart ozone molecules. But during the months when ozone depletion is greatest, giant clouds of ice particlesso-called polar stratospheric cloudsblock the ultraviolet rays. Experts have not completely solved this piece of the ozone destruction puzzle, but according to one theory, the clouds harbor active chlorine molecules. Yet it's not clear how the chlorine would come to be separated from the CFCs in this ultraviolet-free environment.

30. Ozone And The Atmosphere Ozone Formation Formation of the ozone layer. The thin layer of ozone that surrounds Earthacts as a shield, protecting the planet from irradiation by UV light. http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/ATM_CHEM/ozone_formation.html

outline Formation of the Ozone Layer One billion years ago, early aquatic organisms called blue-green algae began using energy from the Sun to split molecules of H O and CO and recombine them into organic compounds and molecular oxygen (O ). This solar energy conversion process is known as photosynthesis. Some of the photosynthetically created oxygen combined with organic carbon to recreate CO molecules. The remaining oxygen accumulated in the atmosphere, touching off a massive ecological disaster with respect to early existing anaerobic organisms. As oxygen in the atmosphere increased, CO decreased. High in the atmosphere, some oxygen (O ) molecules absorbed energy from the Sun's ultraviolet (UV) rays and split to form single oxygen atoms. These atoms combined (27k jpeg) with remaining oxygen (O ) to form ozone (O ) molecules, which are very effective at absorbing UV rays. The thin layer of ozone that surrounds Earth acts as a shield, protecting the planet from irradiation by UV light. The amount of ozone required to shield Earth from biologically lethal UV radiation, wavelengths from 200 to 300 nanometers (nm), is believed to have been in existence 600 million years ago. At this time, the oxygen level was approximately 10% of its present atmospheric concentration. Prior to this period, life was restricted to the ocean. The presence of ozone enabled organisms to develop and live on the land. Ozone played a significant role in the evolution of life on Earth, and allows life as we presently know it to exist.

31. Ozone Layer ozone layer. ozone layer. The ozone layer is a layer in the stratosphere which protectsthe Earth from the harmful effects of ultraviolet radiation from space. http://www.zephryus.demon.co.uk/geography/resources/environ/ozone.html

Ozone Layer Ozone Layer The Ozone layer is a layer in the stratosphere which protects the Earth from the harmful effects of ultra-violet radiation from space. Discussion about the Ozone Layer became popular when, in 1984, it was discovered that above Antarctica there was a hole in the layer. This was not expected and started scientists on a search to discover why the hole had appeared, and what had caused it. For ten or more years before the discovery, scientists had been warning that the use of chlorofluorocarbons ( cfc's ) in products that discharged them into the atmosphere could cause serious damage to the Ozone layer, but it was difficult to prove. The chemical companies which had most to lose if cfc's were banned mounted a strong denial of the suggestion and insisted that cfc's were quite safe, so very little was done to reduce their use. In October 1987 scientists were surprised again when the hole over Antarctica reached the same size as the USA. This increase in size led some scientists to demand immediate action to stop cfc's being used world wide. However, there is a long delay between cfc's being released into the air, and their arrival in the stratosphere. It can take ten years for the gasses to reach the stratosphere, and another one hundred years before they are naturally destroyed. This means that we may have to live with the consequences of past pollution for many years to come.

32. Ozone Layer ozone layer. The ozone stratosphere. The concentration of ozone in theozone layer is usually under 10 parts ozone per million. Without http://www.doc.mmu.ac.uk/aric/eae/Ozone_Depletion/Older/Ozone_Layer.html

Ozone Layer The ozone layer is not really a layer at all, but has become known as such because most ozone particles are scattered between 19 and 30 kilometres (12 to 30 miles) up in the Earth's atmosphere, in a region called the stratosphere . The concentration of ozone in the ozone layer is usually under 10 parts ozone per million. Without the ozone layer, a lot of ultraviolet (UV) radiation from the Sun would not be stopped reaching the Earth's surface, causing untold damage to most living species. In the 1970s, scientists discovered that chlorofluorocarbons (CFCs) could destroy ozone in the stratosphere. Ozone is created in the stratosphere when UV radiation from the Sun strikes molecules of oxygen (O ) and causes the two oxygen atoms to split apart. If a freed atom bumps into another O , it joins up, forming ozone (O ). This process is known as photolysis. Ozone is also naturally broken down in the stratosphere by sunlight and by a chemical reaction with various compounds containing nitrogen, hydrogen and chlorine. These chemicals all occur naturally in the atmosphere in very small amounts. In an unpolluted atmosphere there is a balance between the amount of ozone being produced and the amount of ozone being destroyed. As a result, the total concentration of ozone in the

33. Ozone Layer ozone layer. The ozone layer The concentration of ozone in the ozone layeris usually under 10 parts ozone per million. Without the ozone http://www.doc.mmu.ac.uk/aric/eae/Atmosphere/Older/Ozone_Layer.html

Ozone Layer The ozone layer is a layer of ozone particles scattered between 19 and 30 kilometres (12 to 30 miles) up in the Earth's atmosphere, in a region called the stratosphere . The concentration of ozone in the ozone layer is usually under 10 parts ozone per million. Without the ozone layer, ultraviolet (UV) radiation from the Sun would not be stopped from entering the Earth's atmosphere and arriving at the surface, causing damage to most living species. Ozone is created in the stratosphere when highly energetic solar radiation strikes molecules of oxygen (O ) and causes the two oxygen atoms to split apart. If a freed atom bumps into another O , it joins up, forming ozone (O ). This process known as photolysis. Ozone is also naturally broken down in the stratosphere by sunlight and by a chemical reaction with various compounds containing nitrogen , hydrogen and chlorine. These chemicals all occur naturally in the atmosphere in very small amounts. In an unpolluted atmosphere there is a balance between the amount of ozone being produced and the amount of ozone being destroyed. As a result, the total amount of ozone in the stratosphere remains relatively constant. The amount of ozone within the stratosphere varies according to altitude. Ozone concentrations are highest between 19 and 23 km, but there are significant amounts up to 30 km. At these levels in the atmosphere however, the

34. Greenpeace - Ozone Campaign Industrial society's chemical warfare against the ozone layer during the past sixtyyears has brought grave peril to the well being, indeed, the continuity of http://www.greenpeace.org/~ozone/

Industrial society's chemical warfare against the ozone layer during the past sixty years has brought grave peril to the well being, indeed, the continuity of life on the planet "We are facing a danger as big as humanity has ever faced." Dr. Mostafa Tolba, Former Executive Director of the United Nations Environment Programme, April, 1992, addressing the Open Ended Working Group of the Montreal Protocol, in Geneva. Greenfreeze Greenpeace Campaign to Protect the Ozone Layer (with Slideshow Greenpeace Reports, Position Papers, And Fact Sheets Links To Other Ozone Related Internet Resources Credits And Acknowledgements Return to Greenpeace International's Homepage or the Greenpeace Climate Crisis Homepage Last Update: Send your comments regarding content to: john.mate@green2.greenpeace.org Developed by jot. Send error reports to: tuinman@sfu.ca

35. The Vienna Convention For The Protection Of The Ozone Layer The Vienna Convention for the Protection of the ozone layer. CurrentText for the Vienna Convention English, Français, Español. http://www.unep.ch/ozone/vienna.shtml

Français Español English Nairobi, Sunday March 23 2003 About The Secretariat Ozone Treaties Status of Ratification Reports and Documents ... Contact Addresses The Vienna Convention for the Protection of the Ozone Layer Current Text for the Vienna Convention - English In 1981 the Governing Council set up a working group to prepare a global framework convention for the protection of the Ozone Layer. Its aim was to secure a general treaty to tackle ozone depletion. First, a general treaty resolved in principle to tackle a problem; then the parties got down to the more difficult task of agreeing protocols that established specific controls. Even the first, relatively easy, step proved remarkably difficult. The Convention for the Protection of the Ozone Layer , finally agreed upon in Vienna in 1985, appears unexceptionable. Nations agreed to take "appropriate measures...to protect human health and the environment against adverse effects resulting or likely to result from human activities which modify or are likely to modify the Ozone Layer;" but the measures are unspecified. There is no mention of any substances that might harm the ozone, and

36. Change In The Ozone Layer Change in the ozone layer. Scientists have not been collecting data about the ozonelayer long enough to make concrete decisions about its longterm effects. http://octopus.gma.org/surfing/human/ozonechange.html

Change in the Ozone Layer Scientists have not been collecting data about the ozone layer long enough to make concrete decisions about its long-term effects. Using satellite imagery, students get an idea of the magnitude of annual changes in the ozone layer. Ozone levels are measured in Dobson Units, a measurement of the thickness of pure ozone at normal sea level temperature and pressure. Thus 100 DU equals 1 mm. of pure ozone at sea level. Determine the fate of atmospheric ozone over Antarctica. 1. Discuss with students how ozone levels are measured. 2. Examine one image of ozone concentrations above Antarctica and determine how the different ozone levels are depicted. 3. Starting with the earliest image, trace the magnitude of the ozone hole (if it exists) onto the graph paper and label it. 4. Continue with each subsequent year, noting whether or not there was an increase or decrease in ozone levels. 5. Discuss the trend observed and possible causes. If you had only given the students a few images, would this analysis have reached the same conclusions? 6. Discuss the importance of using satellite imagery in the analysis of the ozone hole. Antarctica is a difficult environment for research, at best. Satellite imagery makes it easy to cover the atmospheric changes on a daily basis. This also allows scientists to examine the changes over time.

37. Ozone Layer I. THE ozone layer AND ITS DEPLETION. The world has changed ostensibly theearth. II. ELEMENTS THAT DESTROY THE ozone layer. The first voice http://www.conama.cl/version_ingles/envi_topics/ozone_layer.htm

COUNTRY PROGRAM FOR THE PROTECTION OF THE OZONE LAYER The Ozone Layer and its Depletion Elements that destroy the Ozone Layer Current Ozone Layer situation and its consequences in Chile The Montreal Protocol ... Ozone Layer Depleting Substances Phase-out in Chile Assessment of Activities and Results 1994-1999 I. THE OZONE LAYER AND ITS DEPLETION Figure 1 :shows a diagram of the energy balance of solar light radiation and its natural filters before arriving on the surface of the earth. II. ELEMENTS THAT DESTROY THE OZONE LAYER The first voice of alert came from a document published in 1974 by the scientists Sh. Rowland and M. Molina at the University of California, who stated that cloroflorocarbons (CFC) used in refrigeration, air conditioning and the production of plastic foam, were responsible for the rapid depletion of the ozone. Many years have passed and subsequent work has confirmed and supported new evidence about the role of chlorine and bromine atoms in a sequence of chemical reactions that destroy the ozone. To summarize, the reaction mechanism can be represented in the following manner: CFC and Halogens (CFBr) are very stable compounds (they can have a half-life of 100 years). Therefore, when they are released into the atmosphere, they are not broken down and reach the stratosphere.

38. The Ozone Layer backgrounder The ozone layer The stratospheric ozone layer protects people,plants, and animals from harmful ultraviolet (UV) radiation. http://www.ucsusa.org/global_environment/connections/page.cfm?pageID=549

39. Ozone Layer Protection Issue The depletion of the ozone layer is a significant global environmental issue,and much has been accomplished to address this issue under the United http://www.agr.gc.ca/policy/environment/eb/public_html/ebe/ozone.html

Issue The depletion of the ozone layer is a significant global environmental issue, and much has been accomplished to address this issue under the United Nation's Montreal Protocol on Substances that Deplete the Ozone Layer . Methyl Bromide, an agricultural soil and space fumigant used in Canada and throughout the world, has been identified under the Protocol as a significant ozone-depleting substance. Although its use in Canada is very low by worldwide standards, the agriculture and agri-food industry has demonstrated leadership in finding alternatives to methyl bromide that will benefit users worldwide. Background At the 1997 meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer, the international community agreed that industrial (developed) countries would freeze their production and consumption of methyl bromide at 1991 levels. These countries agreed to a 25% reduction by 1998, 50% by the year 2001, 70% by the year 2003, and 100% by the year 2005. Developing countries agreed to a 100% phase-out of methyl bromide by the year 2015. At present, Canada has reduced its consumption of methyl bromide by 38%.

40. Thinning Of The Ozone Layer - The Health Effects The Its Your Health fact sheet entitled THINNING OF THE ozone layerTHE HEALTH EFFECTS has been revised. Please update your bookmarks. http://www.hc-sc.gc.ca/ehp/ehd/catalogue/general/iyh/thinning.htm

Previous The "Its Your Health" fact sheet entitled THINNING OF THE OZONE LAYER THE HEALTH EFFECTS has been revised. Please update your bookmarks http://www.hc-sc.gc.ca/english/iyh/ultraviolet.html

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