The ozone layer, depletion and uv radiation on this page: ozone intro | uv radiation | Ozone depleting gases | ecological effects | uv radiation - definitions | phytoplankton . A giant sunshade The ozone layer acts like a giant sunshade, protecting plants and animals from much of the sun's harmful ultraviolet radiation. Ozone (O3) forms a layer in the stratosphere, 15-40 km above earth surface. If the ozone in the atmosphere from ground level to a height of 60 km could be assembled at the earth's surface, it would comprise a layer of gas only about 3 mm thick. Source: Nasa; Shuttle Solar Backscatter Ultraviolett Instrument Global stratospheric ozone levels have declined, which means that the ozone layer is changing. Stratospheric ozone has large natural temporal and spatial variations, up to 30 percent variation may be regarded as normal. However, we now have evidence of a significant thinning of the ozone layer during spring and summer. This is observed in both the northern and the southern hemispheres at middle and high latitudes.

During the last 10-15 years, the ozone layer above the northern hemisphere has been reduced by 5-6 percent in spring per decade. The latest tests (January-March 1995) have shown very large reductions, with a maximum of more than 30 percent reduction compared to normal. Increasing amounts of UV radiation will have an impact on plankton and other tiny organisms at the base of the marine food web. These organisms provide the original food source for all other living organisms in the oceans. Plankton- phytoplankton as well as zooplankton are highly sensitive to UV radiation, as they lack the protective UV-B -absorbing layers that higher forms of plants and animals have. (Phyto = plant. Zoo = animal). More UV-B radiation reduces the amount of food phytoplankton create through photosynthesis. Zooplankton, feeding off the phytoplankton, are also affected. UV-B also damages small fish, shrimp and crab larvae. It has been estimated that on shallow coastal shelves, a 16 percent reduction of the ozone layer would kill more than 50 percent of e.g.

anchovy larvae, and cause a 5 percent drop in plankton numbers and a 6-9 percent drop in fish yield. Global warming Ozone-layer depletion seems likely to increase the rate of greenhouse warming, by reducing the effectiveness of the carbon dioxide sink in the oceans. Phytoplankton in the oceans assimilates large amounts of atmospheric carbon dioxide. Increased UV radiation will reduce phytoplankton activity significantly. This means that large amounts of carbon dioxide will remain in the atmosphere. A 10 percent decrease in carbon dioxide uptake by the oceans would leave about the same amount of carbon dioxide in the atmosphere as is produced by fossil fuel burning. Impact on land plants. A high increase in UV radiation may disrupt many ecosystems on land. Rice production may be drastically reduced by the effects of UV-B on the nitrogen assimilating activities of micro-organisms. With a diminishing ozone layer, it is likely that the supply of natural nitrogen to ecosystems, such as tropical rice paddies, will be significantly reduced.

Most plants (and trees) grow more slowly and become smaller and more stunted as adult plants when exposed to large amounts of UV-B Increased effects of air pollution UV-B stimulates the formation of reactive radicals - molecules that react rapidly with other chemicals, forming new substances. The hydroxyl radicals, for example, stimulate the creation of tropospheric ozone and other harmful pollutants. Smog formation creates other oxidized organic chemicals, such as formaldehydes. These molecules can also produce reactive hydrogen radicals when they absorb UV-B . In urban areas, a 10 percent reduction of the ozone layer is likely to result in a 10-25 percent increase in tropospheric ozone. More UV-B radiation seems likely to cause global increases in atmospheric hydrogen peroxide. This is the principal chemical that oxidizes sulfur dioxide to form sulfuric acid in cloud water, making it an important part of acid rain formation. Damage to materials UV-radiation causes many materials to degrade more rapidly. Plastic materials used outdoors will have much shorter lifetimes with small increases of UV radiation. PVC sidings, window and door frames, pipes, gutters, etc. used in buildings degrade faster.

Source: UNEP/GEMS library series no 7: The Impact of Ozone layer depletion intensity map, and find the estimated UV intensity according to the colour code. Increasing altitude: add 10 % per 1000 metres. With white snow: add 100 % With a decrease in the ozone layer in your area of 10 %: add 20 %. I.e. with a 50 % reduction in the ozone-layer in your region, the UV-intensity increases by approximately 100 %. At sea: add between 5 -10 %. (UV rays are not so much reflected from the water surface, as they mostly penetrate it, and may go deep into the water.) This page is collected from various pages on the "State of the Environment Norway" site. This is well worth checking out if you haven't had enough already! Living With A Star: 3: Balloon/Rocket Mission: Layers of the Atmosphere Main Menu > 3: Balloon/Rocket Mission > Layers of the Atmosphere This drawing shows the different layers of the atmosphere. The ground is shown in brown at the bottom of the picture. The altitude in kilometers is given on the right hand scale and is approximate.

( Click for a larger image .) © UC Regents The Different Levels of the Atmosphere are: Troposphere: This is the lowest atmospheric layer and is about seven miles (11 km) thick. Most clouds and weather are found in the troposphere. The troposphere is thinner at the poles (averaging about 8km thick) and thicker at the equator (averaging about 16km thick). The temperature decreases with altitude. Stratosphere: The stratosphere is found from about 7 to 30 miles (11-48 kilometers) above the Earths surface. In this region of the atmosphere is the ozone layer, which absorbs most of the harmful ultraviolet radiation from the Sun. The temperature increases slightly with altitude in the stratosphere. The highest temperature in this region is about 32 degrees Fahrenheit or 0 degrees Celsius. Mesosphere: The mesosphere is above the stratosphere. Here the atmosphere is very rarefied, that is, thin, and the temperature is decreasing with altitude, about 130 Fahrenheit (-90 Celsius) at the top. Thermosphere: The thermosphere starts at about 55 kilometers.

The temperature is quite hot; here temperature is not measured using a thermometer, but by looking at the motion and speed of the rarefied gases in this region, which are very energetic but would not affect a thermometer. Temperatures in this region may be as high as thousands of degrees. Exosphere: The exosphere is the region beyond the thermosphere. Ionosphere: The ionosphere overlaps the other atmospheric layers, from above the Earth. The air is ionized by the Suns ultraviolet light. These ionized layers affect the transmittance and reflectance of radio waves. Different ioniosphere layers are the D, E (Heaviside-Kennelly), and F (Appleton) regions. This drawing shows the penetration of different kinds of electromagnetic radiation into the atmosphere. Note also the different layers of the ionosphere (D, E, F) and the level at which auroras occur.( Click for a larger image .) © UC Regents Starting at the left: Lightning can generate whistlers, radio waves that can travel long distances. Very high frequency radio waves (VHF) can travel through the atmosphere to and from satellites and are used for communication.

The airglow is due to a chemical reaction in the upper atmosphere that emits light. Many radio waves are reflected at night by the ionosphere making it possible to hear AM radio and shortwave radio stations that are far away. Gamma rays and x-rays are absorbed by the upper atmosphere; visible light can penetrate to sea level. Many infrared wavelengths can also pass through the atmosphere. Related to chapter 3 in the print guide. See Scientific Ballooning to learn how scientists use balloons for research. Click for the definitions of the following words that are used on this page: (Definitions appear in a pop-up window.) The Ozone Layer The Ozone Layer The Solar Spectrum To understand the importance of ozone in the atmosphere, we first must understand the nature of the energy that comes to us from the sun. The sun and other stars are very hot and so radiate energy. Specifically, we call this energy electromagnetic energy. We can characterize electromagnetic radiation according to its wavelength. Remember that the energy of the radiation is inversely proportional to the wavelength. E = hc/ The shape of the intensity vs. wavelength curve depends on the temperature of the emitting object. The higher the temperature, the higher is the maximum intensity and the lower the wavelength of this maximum.

The maximum intensity of the sun's output of radiation is in the visible light region. At the top of the atmosphere, approximately 7% of the radiation is in the ultraviolet, 41% in the visible, and 52% in the infrared. The intensity of electromagnetic radiation that reaches the surface of our planet is considerably less than that at the top of the atmosphere. Something in the atmosphere filters out energy. The highest energy light is most effectively filtered out. This is very important because high energy light (gamma rays, x-rays, UV-radiation) penetrates the cells of living things and causes damage to them. Molecular Filters Consider the figure at right. The magenta filter blocks some wavelength of light, the cyan and yellow filter block others. When the 3 filters are combined, all wavelengths of visible light are blocked and the color appears black. The atmosphere consists of many molecular and atomic filters that each block a certain range of wavelengths of light. With the combined effect of all of these, most of the harmful radiation from the sun is blocked before it reaches the plants and animals on the surface of the Earth. In the highest region of the atmosphere, the ionosphere, atoms such as N absorb very high energy light and lose electrons.

N + energy Below that, in the mesosphere, strongly-bonded molecules such as N2 absorb energy and break apart. N2 + energy 2 N Below that, in the stratosphere, ozone absorbs nearly all the ultraviolet radiation (between 200 and 310 nm). In the lowest region of the atmosphere, the troposphere, colored molecules absorb some visible light and other molecules (H2O, CO2) absorb infrared or heat energy. Ozone in the Stratosphere Ozone has a low concentration throughout the atmosphere but there is a region in the stratosphere where its concentration is higher than anywhere else. About 90% of the ozone in the atmosphere is located within a band centered at 25 km above the surface. Ozone's concentration within the ozone layer is 0.2 to 0.4 ppm. Typical concentrations in unpolluted air closer to the surface is 0.03 ppm. The ozone in the ozone layer absorbs 97-99% of all the ultraviolet light that passes into the stratosphere. The Ozone Hole Until recently, the concentration of ozone in the stratosphere was nearly constant.

However, man-make chemicals such as the FREON used in refrigerators and air conditioners destroy it. Over the course of the winter, reactive molecules build up in stratospheric clouds over the poles. The light and heat of the early spring causes these molecules to combine with ozone, resulting in a hole in the ozone layer. UV radiation can reach the Earth's surface under this hole in the protective ozone layer. International treaties are now limiting the amount of ozone-damaging chemicals that are released. Compass Layers of Earth's Atmosphere - Windows to the Universe Layers of Earth's Atmosphere The Earth's Atmosphere The atmosphere surrounds Earth and protects us by blocking out dangerous rays from the sun. The atmosphere is a mixture of gases that becomes thinner until it gradually reaches space. It is composed of Nitrogen (78%), Oxygen (21%), and other gases (1%). Oxygen is essential to life because it allows us to breathe. Some of the oxygen has changed over time to ozone. The the ozone layer filters out the sun's harmful rays. Recently, there have been many studies on how humans have caused a hole in the ozone layer. Humans are also affecting Earth's atmosphere through the greenhouse effect.

Due to increases in gases, like carbon dioxide, that trap heat being radiated from the Earth, scientists believe that the atmosphere is having trouble staying in balance creating the greenhouse effect . The atmosphere is divided into five layers depending on how temperature changes with height. Most of the weather occurs in the first layer. Layers of the Earth's Atmosphere The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space. The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer. Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun. Meteors or rock fragments burn up in the mesosphere. The thermosphere is a layer with auroras. It is also where the space shuttle orbits. The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere. The Average Temperature Profile of Earth's Atmosphere The Troposphere The troposphere is the lowest layer of the Earth's atmosphere. The air is very well mixed and the temperature decreases with altitude. Air in the troposphere is heated from the ground up.

The surface of the Earth absorbs energy and heats up faster than the air does. The heat is spread through the troposphere because the air is slightly unstable. Weather occurs in the Earth's troposphere. The Stratosphere In the Earth's stratosphere, the temperature increases with altitude. On Earth, ozone causes the increasing temperature in the stratosphere. Ozone is concentrated around an altitude of 25 kilometers. The ozone molecules absorb dangerous kinds of sunlight, which heats the air around them. The stratosphere is located above the top of the the troposphere. Ozone - An Overview The Ozone Hole. Pollution. Skin Cancer. Why does the topic of ozone make the news so much? How important is the ozone in our atmosphere? Why are scientists so concerned about its increase near the surface of the Earth and its disappearance higher up in the atmosphere? First things first - what is ozone? Ozone is made of three oxygen atoms (O3). The oxygen in our atmosphere that we breathe is made up of two oxygen atoms (O2). When enough ozone molecules are present, it forms a pale blue gas. Ozone has the same chemical structure whether it is found in the stratosphere or the troposphere.

Where we find ozone in the atmosphere determines whether we consider it to be "good" or "bad"! In the troposphere, the ground-level or "bad" ozone is an air pollutant that damages human health, vegetation, and many common materials. It is a key ingredient of urban smog. In the stratosphere, we find the "good" ozone that protects life on Earth from the harmful effects of the Sun's ultraviolet rays. We have good reason to be concerned about the thinning of the ozone layer in the stratosphere. We also have good reason to be concerned about the buildup of ozone in the troposphere. Although simplistic, the saying "Good up high and bad near by," sums up ozone in the atmosphere. Ozone in the Stratosphere About 90% of the ozone in the Earth's atmosphere is found in the region called the stratosphere. This is the atmospheric layer between 16 and 48 kilometers (10 and 30 miles) above the Earth's surface. Ozone forms a kind of layer in the stratosphere, where it is more concentrated than anywhere else.

Ozone and oxygen molecules in the stratosphere absorb ultraviolet light from the Sun, providing a shield that prevents this radiation from passing to the Earth's surface. While both oxygen and ozone together absorb 95 to 99.9% of the Sun's ultraviolet radiation, only ozone effectively absorbs the most energetic ultraviolet light, known as UV-C and UV-B. This ultraviolet light can cause biological damage like skin cancer, tissue damage to eyes and plant tissue damage. The protective role of the ozone layer in the upper atmosphere is so vital that scientists believe life on land probably would not have evolved - and could not exist today - without it. The ozone layer would be quite good at its job of protecting Earth from too much ultraviolet radiation - that is, it would if humans did not contribute to the process. It's now known that ozone is destroyed in the stratosphere and that some human-released chemicals such as CFCï¿½s are speeding up the breakdown of ozone, so that there are "holes" now in our protective shield. While the stratospheric ozone issue is a serious one, in many ways it can be thought of as an environmental success story.

Scientists detected the developing problem, and collected the evidence that convinced governments around the world to take action. Although the elimination of ozone-depleting chemicals from the atmosphere will take decades yet, we have made a strong and positive beginning. For the first time in our species' history, we have tackled a global environmental issue on a global scale. The Mesosphere In the Earth's mesosphere, the air is relatively mixed together and the temperature decreases with altitude. The atmosphere reaches its coldest temperature of around -90ï¿½C in the mesosphere. This is also the layer in which a lot of meteors burn up while entering the Earth's atmosphere. The mesosphere is on top of the stratosphere The upper parts of the atmosphere, such as the mesosphere, can sometimes be seen by looking at the very edge of a planet. The Thermosphere The thermosphere is the fourth layer of the Earth's atmosphere and is located above the mesosphere. The air is really thin in the thermosphere. A small change in energy can cause a large change in temperature. That's why the temperature is very sensitive to solar activity. When the sun is active, the thermosphere can heat up to 1,500ï¿½ C or higher!

The Earth's thermosphere also includes the region of the atmosphere called the ionosphere. The ionosphere is a region of the atmosphere that is filled with charged particles. The high temperatures in the thermosphere can cause molecules to ionize. This is why an ionosphere and thermosphere can overlap. The Ionosphere Scientists call the ionosphere an extension of the thermosphere. So technically, the ionosphere is not another atmospheric layer. The ionosphere represents less than 0.1% of the total mass of the Earth's atmosphere. Even though it is such a small part, it is extremely important! The upper atmosphere is ionized by solar radiation. That means the Sun's energy is so strong at this level, that it breaks apart molecules. So there ends up being electrons floating around and molecules which have lost or gained electrons. When the Sun is active, more and more ionization happens! Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth. It is also home to auroras. Temperatures in the ionosphere just keep getting hotter as you go up! Regions of the Ionosphere The ionosphere is broken down into the D, E and F regions.

The breakdown is based on what wavelength of solar radiation is absorbed in that region most frequently. The D region is the lowest in altitude, though it absorbs the most energetic radiation, hard x-rays. The D region doesn't have a definite starting and stopping point, but includes the ionization that occurs below about 90km. The E region peaks at about 105km. It absorbs soft x-rays. The F region starts around 105km and has a maximum around 600km. It is the highest of all of the regions. Extreme ultra-violet radiation (EUV) is absorbed there. On a more practical note, the D and E regions reflect AM radio waves back to Earth. Radio waves with shorter lengths are reflected by the F region. Visible light, television and FM wavelengths are all too short to be reflected by the ionosphere. So your t.v. stations are made possible by satellite transmissions. This image shows how the ionosphere is divided even further into layers: D, E, and F layers. The Sun's Effect on the Ionosphere Invisible layers of ions and electrons are found in the Earth's atmosphere. We call this region of atmosphere the ionosphere.

The main source of these layers is the Sun's ultraviolet light which ionizes atoms and molecules in the Earth's upper atmosphere. During this process, electrons are knocked free from molecules or particles in the atmosphere. Flares and other big events on the Sun produce increased ultraviolet, x-ray and gamma-ray photons that arrive at the Earth just 8 minutes later (other particles from the Sun may arrive days later) and dramatically increase the ionization that happens in the atmosphere. So, the more active the Sun, the thicker the ionosphere! This image shows how different types of solar radiation (x-rays to infrared radiation) penetrate into the Earth's atmosphere. It is this solar radiation that ionizes the upper atmosphere, creating the ionosphere. The Exosphere Very high up, the Earth's atmosphere becomes very thin. The region where atoms and molecules escape into space is referred to as the exosphere. The exosphere is on top of the thermosphere. Last modified September 1, 2010 by Randy Russell . Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist , which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earthï¿½s ancient atmosphere, is available in our online store . Windows to the Universe Community News Example Essays: Ozone Layer Stratosphere 1. The Disappearing Ozone Layer Ozone LayerThe ozone layer refers to a region of Earth's stratosphere that absorbs most of the Sun's UV radiation. ... The ozone layer contains less than ten parts per million of ozone, while the average ozone concentration in Earth's atmosphere as a whole is only about 0.6 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 20 to 30 kilometers above Earth, though the thickness varies seasonally and geographically. The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson.... Word Count: 1264 2. the ozone layer Ozone located approximately 10-25 miles above the Earth"s surface, in a part of the Earth"s atmosphere called the stratosphere is very beneficial. ...

About 90% of the planet"s ozone is in the ozone layer. ... Since CFCs are heavier than air, the process of CFCs reaching the ozone will generally take from two to five years to get into the stratosphere. When CFCs reach the stratosphere, the sun"s ultraviolet radiation cause them to break apart. ... The effects of poisoning of the ozone layer will lash out on the marine ecosystem. ... Word Count: 2237 3. The Ozone Layer The Ozone LayerIntroductionThe ozone layer is one of the most important source of protection that exists on Earth. ... The ozone layer has provided protection for the living components under it for millions of years, and without the ozone layer, we most likely would not be here today. The ozone layer is a layer of ozone particles scattered between 19 and 30 kilometers up in the earth's atmosphere. ... Over Antarctica, stratospheric ozone has been depleted over the last 15 years at certain times of the year. ... Atmospheric layers, as measured in distance from the Earth's surface, ar... Word Count: 2476 4.

Ozone Layer The stratosphere extends from 12km"s to 50km"s above the earths surface. The ozone layer ranges from 15km to 35km. What scientists have been and still are working out, are the chemical reactions that take place in this ozone layer. ... This helps us understand the chemistry in the stratosphere as it tells us what is likely to be found there and what height the ozone is found at. ... Then, Sherwood Rowland found that CFCs will absorb the high energy ultra-violet radiation and release Cl* in the stratosphere. in 1987, Farman discovered the ozone hole by measurement. ... Word Count: 1186 5. Earth's Atmosphere and the Ozone Layer The ozone layer is a layer of the second layer of Earth's atmosphere, the stratosphere (Dunn, 1993). ... The ozone hole, which actually isn't a hole but a very thin layer of ozone gas over Antarctica, is caused by chlorofluorocarbons, also known as CFCs. ... This compound is damaging to the ozone layer when the sun's ultraviolet rays break it down, releasing chlorine. ...

The lack of ozone in our stratosphere is affecting not only Antarctica but the whole world as well. ... Lastly, if we observe this situation on a global point of view, we will notice how many problems are cause... Word Count: 800 6. Depletion Of The Ozone Layer The next layer, the stratosphere, continues from 10 to 50 kilometers. ... Most atmospheric ozone is concentrated in a layer in the stratosphere, about 15 to 30 kilometers above the Earth"s surface. ... Scientists are finding that under this assault the protective ozone layer in the stratosphere is thinning. ... The ozone layer is composed of two parts, the troposphere and the stratosphere. ... Most atmospheric ozone is concentrated in a layer in the stratosphere, about 15 to 30 kilometers above the Earth"s surface. ... Word Count: 2746 7. ozone layer The next result of these natural processes is the so-called ozone layer in the stratosphere at altitudes between 9 and 30 miles in which the concentration of the ozone is raised. ... However, ozone concentrations are not static, winds transport, ozone throughout the stratosphere. ...

How did scientist become concerned about the ozone layer?... The research on the stratospheric effects of shuttle launches altered others in the scientific community and in government agencies to view chlorine compounds as possible threats to the ozone layer (NAS). ... "Stratospheric Ozone.aE Environment Can... Word Count: 1049 9. ozone depletion The Ozone LayerTwo decades ago stratospheric ozone depletion was mainly the interest of atmospheric scientists. ... Nearly 90% of the Earth's ozone is situated in the stratosphere, the atmosphere layer between 10 to 40 kilometers above Earth's surface, where it is continuously generated and destroyed by the UV radiation. ... Only a small portion of ozone is in the troposphere, the internal atmospheric layer. ... A depletion of the ozone layer will increase the UV radiation at ground level. ... For each 10% depletion of the ozone layer, we can expect 20% more radiation in these wavele... Word Count: 1505 10. Ozone Depletion The Ozone LayerTwo decades ago stratospheric ozone depletion was mainly the interest of atmospheric scientists. ...

Nearly 90% of the Earth's ozone is situated in the stratosphere, the atmosphere layer between 10 to 40 kilometers above Earth's surface, where it is continuously generated and destroyed by the UV radiation. ... Only a small portion of ozone is in the troposphere, the internal atmospheric layer. ... A depletion of the ozone layer will increase the UV radiation at ground level. ... For each 10% depletion of the ozone layer, we can expect 20% more radiation in these wavele... Word Count: 1470 11. depletion of ozone layer Depletion of the Ozone LayerCHEM 151 Research PaperJuly 11, 1996 The ozone layer diminishes more each year. ... These rays cause cancer, cataracts, and lowered immunity to diseases.1 What causes the depletion of the ozone layer?... The sulfate aerosols cause chemical reactions in addition to chlorine and bromine reactions on stratospheric clouds that destroy the ozone.8Some ozone depletion is due to volcanic eruptions. ... Also, chlorine and bromine react well under cold temperatures 15-20 kilometers up in the stratosphere where mosof the ozone is lost. ...

The remainder breaks down under... Word Count: 1167 12. Depletion of the Ozone Layer The Depletion of the Ozone Layer People throughout the world are voicing concern with the environment. ... One problem that is important to all of us is the depletion of the ozone layer. ... Then the chlorine atoms react with ozone, start chemical cycles of ozone destruction that depletes the ozone layer (Christie 15). ... There are many consequences involved in the destruction of the Ozone layer. ... The actions of humans have had a detrimental effect on the ozone layer. ... Word Count: 1231 14. The Ozone Molecule Ozone molecules can be found in the stratosphere and troposphere layers of the atmosphere. However, the majority of ozone is found in the stratosphere between 10 and 30 miles above the earth's surface. The ozone layer was originally created by early organisms called blue-green algae. ...

Before ozone life could only be found in the ocean but the ozone layer allowed organisms to develop and evolve until they could live on land.All around us we hear about the holes in the ozone layer, but at the same time we hear about scientist worried about having too much ozone. ... While the ozone in t... Word Count: 487 17. Arctic Ozone Depletion Below, I will explain the potential causes of the newest hole in the ozone layer, citing responses from environmentalists and scientists, and outline some measures that have been proposed to slow the depletion of the ozone layer, or at least lessen its effect on the Earth"s population.What is the ozone layer?Ozone, a mixture of oxygen and carbon monoxide and dioxide, exists in the stratosphere, above the "breathableaE atmosphere of the Earth. ... But above the inhabited layer of the atmosphere, the ozone layer is depleted by the presence of nitrites and nitrates in stratospheric cloud f... Word Count: 1616 18. Ozone Layer 2 The ozone layer shields the earth from most of the harmful radiation and light comming from the sun. ...

Skin cancer develops in most living mammals as a cause of an overabundance of the suns ultraviolet rays.The ozone layer is located in the earth's stratosphere. The ozone layer is located from about fifteen-to-thirty kilometers above the earths surface. ... The ozone is colored blue and has a remarkably strong odor. The ozone molecule is a very rare molecule. ... Word Count: 620 19. Where Is The Ozone The ozone layer reflects most of the ultraviolet radiation from the sun back into space. ... Moving down through the stratosphere, the air becomes denser, ultraviolet radiation absorption increases and ozone levels increase. ... The layer of ozone formed in the stratosphere by these reactions is sometimes called the SChapman layeraE. ... Most countries now have phased out the use of CFCs and methyl bromide in response to international agreements to protect the ozone layer. However, because CFCs remain in the atmosphere so long, the ozone layer will not fully repair itself until at leas... Word Count: 862 20.

Ozone Depletion In fact, 50 years ago they could be found as refrigerants, solvents and blowing agents, but back then they had no idea that CFCs would eventually cause the breakdown of the ozone layer over Antarctica.In 1970 researchers started to observe different chemicals found in the ozone layer. ... CFC"s have altered the natural ozone cycle in the stratosphere. ... With less ozone in the stratosphere, every CFC becomes more dangerous and has a greater effect on the total ozone left in the atmosphere. ... Naturally occurring chlorine has the same effect in the ozone layer, but has a shorter life span. ... Word Count: 1635 21. Global Depletion The lowest region, the troposphere, the next layer, the stratosphere, and the most atmospheric ozone are concentrated in a layer in the stratosphere, about 15aE"30 kilometers above the Earth's surface. ... When the ozone layer begins to thin, it lets more UV rays enter our atmosphere. At any given time, ozone molecules are constantly formed and destroyed in the stratosphere. ... It has been proven that the ozone layer has diminished by 3%. ...

The ozone layer is thinning; and the thinner it gets the more that future will continue to haunt us. ... Word Count: 942 22. Our Ozone The ozone layer is a region of the atmosphere that protects us from the harmful effects of the sun. ... Scientists discovered in the 1970"s that chemicals that we had been using regularly were damaging the earth"s protective layer. ... Damage to the ozone layer is expected to cause higher rates of skin cancer, cataracts, crop damage, the marine food cycle, and an increase in carbon dioxide, which contributes to global warming. ... Which is cold enough to create polar stratospheric clouds, in these clouds a reaction between the chemicals takes place and converts the inactive chlorine and bro... Word Count: 1083 23. Ozone One realization is that the ozone layer is weakening. ... The ozone is a protective layer that absorbs UV-B. ... About 90% of ozone is found in the stratosphere, which is 6 to 30 miles above the earth's surface. Stratospheric ozone is beneficial because of the UV absorption. ... They discovered that CFCs could destroy ozone in the stratosphere. ...

Word Count: 3086 24. Depletion of the Ozone This depletion of the ozone layer has long-term effects that are harmful to us all. ... Ozone forms a layer in the stratosphere, thinnest in the tropics (around the equator) and denser towards the poles. ... A small band between nine and twenty-two miles high in the stratosphere is what we call the ozone layer. It is very sensitive, and ozone is rare even in the ozone layer. ... HCFCs have less chlorine in them and are less susceptible to the reactions that release chlorine in the stratosphere. ... Word Count: 977 25. What the World Can do About Global Warming, the Greenhouse E What the World Can do About Global Warming, the Greenhouse Effect and the Ozone Layer?... The ozone is a "pure form of oxygen found in the stratosphere ten to thirty miles above the earth"s surface, acts like a big umbrella to protect the earth from dangerous ultraviolet rays of the sun. it is the only gas in the atmosphere that limits the amount of harmful solar ultraviolet radiation reaching the earth . . .

[and] small changes in the ozone concentrations could have dramatic effects on life on earthaE(MacEachern 16). ... Humans are a big part of the problem and solution; therefore, lim... Word Count: 981 Science - Ozone Basics Where is ozone found in the atmosphere? Ozone is mainly found in two regions of the Earth's atmosphere. Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kilometers) above the Earth's surface and extends up to about 30 miles (50 kilometers). This region of the atmosphere is called the stratosphere. The ozone in this region is commonly known as the ozone layer. The remaining ozone is in the lower region of the atmosphere, which is commonly called the troposphere. The figure (above) shows an example of how ozone is distributed in the atmosphere. What roles does ozone play in the atmosphere and how are humans affected? The ozone molecules in the upper atmosphere (stratosphere) and the lower atmosphere (troposphere) are chemically identical, because they all consist of three oxygen atoms and have the chemical formula O3.

However, they have very different roles in the atmosphere and very different effects on humans and other living beings. Stratospheric ozone (sometimes referred to as "good ozone") plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself (a region in which the temperature rises as one goes to higher altitudes). Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. Many experimental studies of plants and animals and clinical studies of humans have shown the harmful effects of excessive exposure to UV-B radiation. At the Earth's surface, ozone comes into direct contact with life-forms and displays its destructive side (hence, it is often called "bad ozone"). Because ozone reacts strongly with other molecules, high levels of ozone are toxic to living systems. Several studies have documented the harmful effects of ozone on crop production, forest growth, and human health.

The substantial negative effects of surface-level tropospheric ozone from this direct toxicity contrast with the benefits of the additional filtering of UV-B radiation that it provides. What are the environmental issues associated with ozone? The dual role of ozone leads to two separate environmental issues. There is concern about increases in ozone in the troposphere. Near-surface ozone is a key component of photochemical "smog," a familiar problem in the atmosphere of many cities around the world. Higher amounts of surface-level ozone are increasingly being observed in rural areas as well. There is also widespread scientific and public interest and concern about losses of ozone in the stratosphere. Ground-based and satellite instruments have measured decreases in the amount of stratospheric ozone in our atmosphere. Over some parts of Antarctica, up to 60% of the total overhead amount of ozone (known as the column ozone) is depleted during Antarctic spring (September-November). This phenomenon is known as the Antarctic ozone hole. In the Arctic polar regions, similar processes occur that have also led to significant chemical depletion of the column ozone during late winter and spring in 7 out of the last 11 years.

The ozone loss from January through late March has been typically 20-25%, and shorter-period losses have been higher, depending on the meteorological conditions encountered in the Arctic stratosphere. Smaller, but still significant, stratospheric decreases have been seen at other, more-populated regions of the Earth. Increases in surface UV-B radiation have been observed in association with local decreases in stratospheric ozone, from both ground-based and satellite-borne instruments. What human activities affect upper-atmospheric ozone (the stratospheric ozone layer)? The scientific evidence, accumulated over more than two decades of study by the international research community, has shown that human-produced chemicals are responsible for the observed depletions of the ozone layer. The ozone-depleting compounds contain various combinations of the chemical elements chlorine, fluorine, bromine, carbon, and hydrogen and are often described by the general term halocarbons. The compounds that contain only chlorine, fluorine, and carbon are called chlorofluorocarbons, usually abbreviated as CFCs.

CFCs, carbon tetrachloride, and methyl chloroform are important human-produced ozone-depleting gases that have been used in many applications including refrigeration, air conditioning, foam blowing, cleaning of electronics components, and as solvents. Another important group of human-produced halocarbons is the halons, which contain carbon, bromine, fluorine, and (in some cases) chlorine and have been mainly used as fire extinguishants. What actions have been taken to protect the ozone layer? Through an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer, governments have decided to eventually discontinue production of CFCs, halons, carbon tetrachloride, and methyl chloroform (except for a few special uses), and industry has developed more "ozone-friendly" substitutes. All other things being equal, and with adherence to the international agreements, the ozone layer is expected to recover over the next 50 years or so.

* Text and figure are adapted from the Introduction to "Frequently Asked Questions" of the World Meteorological Organization/United Nations Environment Programme report, Scientific Assessment of Ozone Depletion: 1998 (WMO Global Ozone Research and Monitoring Project-Report No. 44, Geneva, 1999). Introduction to Ozone: Background Material Introduction to Ozone This section provides an overview of ozone and why it is considered to be 'bad' when found in the troposphere, and 'good' when found in the stratosphere. Ozone has the same chemical structure whether it is found in the stratosphere or troposphere. The general concepts found in this section include the following: Ozone is a form of oxygen. The molecule contains three oxygen atoms ( .) Ozone is unstable and will readily combine with other atoms. Ozone is found in the stratosphere, where it blocks the sun's ultraviolet (UV) waves and prevents them from reaching the earth's surface. Ozone is also found in the troposphere, where it can damage living tissue and human-produced objects. It is generated both from certain types of pollution and natural sources. This section includes four classroom activities. Introduction The Ozone Hole.

The Ozone Hoax. Pollution. Skin Cancer. The topic of ozone makes headlines on a regular basis, but why does a single molecule merit such media coverage? How important is the ozone in our atmosphere and why are scientists so concerned about its increase near the surface of the earth and its disappearance higher up in the atmosphere? First things first - what is ozone? Ozone is made of three oxygen atoms ( ). The oxygen we find in our atmosphere is made up of two oxygen atoms ( ). Because of its chemical formulation, a single atom of oxygen (O) is unstable. That is, it wants to combine with something else. That is why oxygen is almost always found in pairs, in its (diatomic) form, where it is more stable. is less stable than , because it wants to return to the diatomic state by giving up an oxygen atom. When enough ozone molecules are present, it forms a pale blue gas. It is an unstable molecule that readily combines with other atoms. Ozone has the same chemical structure whether it is found in the stratosphere or the troposphere. Where we find ozone in the atmosphere determines whether we consider it to be Dr. Jekyll or Mr. Hyde.

In the troposphere, the ground-level or "bad" ozone is an air pollutant that damages human health, vegetation, and many common materials. It is a key ingredient of urban smog. In the stratosphere, we find the "good" ozone that protects life on earth from the harmful effects of the sun's ultraviolet rays. Electromagnectic Spectrum To understand how ozone is generated and the functions it serves in the earth's atmosphere, it is important to know something about the electromagnetic spectrum  the energy emitted from the sun. Electromagnetic energy is sometimes described as traveling in waves and sometimes as traveling in packets of energy referred to as photons. Progressing from short wavelengths to long wavelengths, scientists have identified gamma rays, x-rays, ultraviolet radiation, visible light (between 400 and 700 nanometers), infrared radiation (heat), microwaves, and radio waves. Short wavelengths have more energy per photon than long wavelengths. Ozone is constantly being formed in the earth's atmosphere by the action of the sun's ultraviolet radiation on oxygen molecules. Ultraviolet light splits the molecules apart by breaking the bonds between the atoms.

A highly reactive free oxygen atom then collides with another oxygen molecule to form an ozone molecule. Because ozone is unstable, ultraviolet light quickly breaks it up, and the process begins again. Ozone in the Stratosphere Ozone and oxygen molecules in the stratosphere absorb ultraviolet light from the sun, providing a shield that prevents this radiation from passing to the earth's surface. While both oxygen and ozone together absorb 95 to 99.9% of the sun's ultraviolet radiation, only ozone effectively absorbs the most energetic ultraviolet light, known as UV-C and UV-B, which causes biological damage. The protective role of the ozone layer in the upper atmosphere is so vital that scientists believe life on land probably would not have evolved - and could not exist today - without it. The term "shield" as a description of ozone in the stratosphere is a bit misleading because the molecules do not form an impermeable sphere around the earth. Ozone continuously breaks apart into its oxygen atoms and reforms as ozone molecules, so a particular ozone molecule doesn't last very long.

The "shield" changes constantly, but the atmospheric chemical processes maintain a dynamic equilibrium that keeps the overall amount of ozone constant - that is, it would if humans did not contribute to the chemical processes. About 90% of the ozone in the earth's atmosphere lies in the region called the stratosphere between 16 and 48 kilometers (10 and 30 miles) above the earth's surface. Ozone forms a kind of layer in the stratosphere, where it is more concentrated than anywhere else, but even there it is relatively scarce. Its concentrations in the ozone layer are typically only 1 to 10 parts of ozone per 1 million parts of air, compared with about 210,000 parts of oxygen per 1 million parts of air. Ozone in the Troposphere The other 10% of the ozone in the earth's atmosphere is found in the troposphere, which is the portion of the atmosphere from the earth's surface to about 12 km or 7 miles up. In the troposphere, ozone is not wanted.

Ozone is even more scarce in the troposphere than the stratosphere with concentrations of about 0.02 to 0.3 parts per million. But even in such small doses, this molecule can do a lot of damage. And just to confuse things even further, ozone in the troposphere is one of the greenhouse gases. As discussed in the Greenhouse Effect section, the naturally occurring greenhouse gases (including ozone) are what make earth habitable for life as we know it. But scientists are very concerned about the warming effects of increased greenhouse gases caused by human activity. So, in the troposphere, accelerated ozone levels deal us a double whammy - as a key ingredient in smog and as a powerful greenhouse gas. Concluding Thoughts Ozone is found in two different layers of the atmosphere - the troposphere and the stratosphere. The stratospheric ozone, or "good ozone," protects life on earth from harmful effects of the sun's UV rays. We have good reason to be concerned about the thinning of the ozone layer in the stratosphere. Tropospheric ozone, or "bad ozone," is an air pollutant that damages human health, vegetation, and many common materials.

We have good reason to be concerned about the buildup of ozone in the troposphere. In this and the following sections, we will explore the various aspects of ozone to help your students better understand this complex, and sometimes seemingly contradictory, molecule. Although simplistic, the saying "Good up high and bad near by," sums up ozone in the atmosphere. Activities

Question: which region of the earth's stratosphere traps most of the sun's UV radiation?
Answer: The Ozone LAYER.