This together with an unusual wind pattern above the S. Pole in the winter (the polar vortex) are thought to create the ozone hole when the sun returns in the spring. OBSERVED OZONE CHANGES. These high altitude clouds form only at very low temperatures help destroy ozone in two ways. ARCTIC OZONE DEPLETION LINKED TO LONGEVITY OF POLAR STRATOSPHERIC CLOUDS. Its beautiful colors result from the very small size of the ice crystals it contains. Topic: Conservation, environmental pollution and degradation, environmental impact assessment. ... but also air temperatures low enough to form polar stratospheric clouds (PSCs). Manned flights involve remote and hazardous duty, which pose great risks to pilots, crew, and scientists. Extremely low stratospheric temperatures (lower than -78(C) over the Antarctic region contribute to depletion of ozone, in that low temperatures lead to the presence of polar stratospheric clouds … Arctic ozone depletion observed in the Spring of 2010 by satellites, manned aircraft campaigns and ground stations was less severe than that observed in 2011. Dynamite in a fluffy package: The shocking Antarctic ozone losses had many scientists intrigued, including atmospheric chemist Susan Solomon. Part2: Threats against ozone. This figure shows the area within the polar vortex that has temperatures low enough to form Polar Stratospheric Clouds (PSCs). [1982] using Stratospheric The paper also emphasized the need for polar stratospheric clouds to explain the reaction chemistry. Generally, we find thinning or depletion of the ozone layer to the extent of ozone hole creation over the southern pole i.e. Also in 1986, Michael B. McElroy and colleagues described a role for bromine in ozone-depleting reactions. The 2016 relationship is shown as the blue diamond. Racking her brain for something that might be … cause polar stratospheric clouds (PSCs) to form. (250 words) Geography by G C Leong The nitric acid in polar stratospheric clouds reacts with chlorofluorocarbons to form chlorine, which catalyzes the photochemical destruction of ozone. compounds. “ozone hole” occurs because of the special weather conditions that exist there and nowhere else on the globe. As a consequence, Arctic stratospheric air is generally much warmer than in the Antarctic, and fewer clouds form there. Polar stratospheric clouds (PSCs). Polar vortex and ozone depletion are two distinct but related phenomena. Experts have not completely solved this piece of the ozone destruction puzzle, but according to one theory, the clouds … In addition to this well-known stratospheric ozone depletion, there are also tropospheric ozone depletion events, which occur near the surface in polar regions during spring. Thus, fallout of the con- In addition, the stratosphere remained cold, leading to the formation of polar stratospheric clouds, which allowed chemical reactions to release reactive forms of chlorine and cause ozone depletion. research is to study stratospheric ozone depletion in polar regions. Factors responsible for the depletion of ozone: Depletion of ozone is due to many factors, the most dominant of which is the release of chlorine from CFCs (Chlorofluorocarbons) which destroys the ozone. The amount of ozone over the South Pole reached a minimum of 104 Dobson units on Oct. 12 — making it the 12th lowest year out of 33 years of NOAA ozonesonde measurements at the South Pole, according to NOAA scientist Bryan Johnson. magnitude for that eruption) and thereby increase polar ozone loss [e.g., Deshler et al., 1994; Portmann et al., 1996; Bregman et al., 1997], whether smaller volcanic enhancements in stratospheric sulfate aerosol abundances could have had some influence on polar ozone depletion received less attention. Depletion of ozone is due to increase in halocarbons in the atmosphere. that protects humans and other living things from harmful ultraviolet (UV) radiation from Insights has redefined the way preparation is done in UPSC civil service exam. 3. Chlorine chemistry. The persistent southern vortex has profound implications for polar ozone loss. in increased condensation of nitric acid in polar stratospheric clouds. The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. A second feature of the polar stratosphere that is unique and probably aids the polar ozone depletion is polar stratospheric clouds. This particular cloud formation appeared over Iceland at an altitude of about 22 km on February 4, 2003. Manned flights involve remote and hazardous duty, which pose great risks to pilots, crew, and scientists. Polar Stratospheric clouds Also called Nacreous clouds, these are formed at very high altitudes, between 15 and 25 km and at very cold temperatures often in winter near the North or South Pole. The ice crystals that make up these PSCs are where heterogeneous photo-chemical destruction of ozone take place. Polar stratospheric clouds create the conditions for drastic ozone destruction, providing … Scientists recently discovered that polar stratospheric clouds, long known to play an important role in Antarctic ozone destruction, are occurring with increasing frequency in the Arctic. OGP InstaClasses- Classroom Program - 2022 (Online & Offline) Year-Long Mains Test Series - 2021; As these clouds are more persistent in the South Pole, we have a larger hole in the Antarctic atmosphere. https://neostencil.com/ozone-hole-causes-and-measures-to-mitigate exposure to ultraviolet light in the stratosphere breaks them down into more reactive gases. Therefore, the ozone depletion in … This creates the ozone hole, which occurs because of special meteorological and chemical conditions that exist in that region. Polar Stratospheric Clouds and Ozone Depletion Clouds rarely form in the dry, Antarctic stratosphere, but when they do, they chemically conspire with chlorofluorocarbons to create the "ozone hole" that opens up every spring by Owen B. Toon and Richard P. Turco More than two dozen scientists boarded a … Ozone depletion occurs in such polar stratospheric clouds. The ozone hole is formed each year in the Southern Hemisphere spring (September-November) when there is a sharp decline (currently up to 60%) in the total ozone over most of Antarctica. Readings: Turco: p. 422-432, 440-443; Brimblecombe: 195-202. Stratospheric Climate Change Antarctic Ozone Hole • Caused pronounced cooling in the lower stratosphere in austral spring • Ozone depletion has resulted in a seasonal strengthening of the polar vortex and shifting of the tropospheric jet (positive trend in the SAM) • … The … . The special conditions that make ozone depletion most severe over polar regions (esp. Summary of what happens in the Anarctic hole For details of the chemistry of … surface are expected to be more influenced by factors other than stratospheric ozone depletion (such as changes in clouds, atmospheric fine particles, and air quality in the lower atmosphere). Their findings indicate that chlorine may hibernate in condensed, non-reactive phase during the frigid Antarctic winter, residing in polar stratospheric clouds or in some molecular state not yet identified. Powerful winds have caused cold air to get trapped in the polar vortex. The severe depletion of the Antarctic ozone layer known as the “ozone hole” occurs because of the special weather conditions that exist there and nowhere else on the globe. Figure Q9-1. Experts have not completely solved this piece of the ozone destruction puzzle, but according to one theory, the clouds … In warmer temperatures like this year, fewer polar stratospheric clouds form and they don’t persist as long, limiting the ozone-depletion process. Polar stratospheric cloud definition, an iridescent cloud in the winter polar stratosphere, as high as 15.5 miles (25 kilometers) above the earth: in both the Antarctic and the Arctic, these clouds contribute to ozone depletion by converting benign forms of chlorine into ozone-destroying forms and by eliminating the nitrogen compounds that curb the destructive effects of chlorine. Fortunately, the temperature has been increasing in the Arctic since the last few days in April that has allowed the ozone hole to close. The polar stratosphere becomes very cold in winter because of the absence of sunlight and because strong winds isolate the polar air. Polar Stratospheric Clouds Low stratospheric temperatures result in “ice clouds” called Polar Stratospheric Clouds (Crutzen, et. Extremely low stratospheric temperatures (lower than -78(C) over the Antarctic region contribute to depletion of ozone, in that low temperatures lead to the presence of polar stratospheric clouds (PSCs). The severe depletion of the Antarctic ozone layer known as the “ozone hole” occurs because of the special atmospheric and chemical conditions that exist there and nowhere else on the globe. With springtime warming, the chlorine emerges from these reservoirs in reactive, ozone-destroying vapor. Special reactions that occur on PSCs and the relative isolation of polar stratospheric air allow chlo- . Polar stratospheric clouds (PSCs) form seasonally over the polar regions. Ozone depletion is highly dependent on the formation of polar stratospheric clouds, which accumulate chlorine and bromine compounds in the cold polar night and then release these ozone-eaters when the sunlight of spring returns. Stratospheric ozone filters out a large part of the ultraviolet (UV) radiation emitted by the sun, protecting life on Earth.Enhanced UV-B radiation (280 to 320 nm) can have a negative impact on photosynthesis, cause skin cancer and weaken the immune system. This e"ect is particularly strong in the southern hemisphere, where the polar vortex is colder and more stable than northern counterpart. Dramatic springtime depletions of ozone in polar regions require that polar stratospheric air has a high degree of dynamical isolation and extremely cold temperatures necessary for the formation of polar stratospheric clouds. particular, chemical reactions that cause ozone depletion take place on the surfaces of clouds and aerosols. But during the months when ozone depletion is greatest, giant clouds of ice particles–so-called polar stratospheric clouds–block the ultraviolet rays. Their surfaces act as a catalyst which converts chlorine molecules into free radicals and therefore speeds up ozone depletion. Polar Stratospheric Cloud Background These clouds exist at very high altitude (~70,000 ft) within Earth's stratosphere.Clouds do not normally form in the stratosphere due to its extreme dryness. stratospheric ozone andyor atmospheric greenhouse gas concen-trations. from total ozone changes Averages Uncertainty ranges. Popular Courses. Polar stratospheric clouds can form at temperatures below about 195 K. Chemical reactions on the surfaces of the particles that form these clouds convert chlorine compounds from inert forms into highly reactive species. 1.2.2c Polar Stratospheric Clouds Traditional gas phase chemistry alone cannot account for the magnitude of ozone destruction observed in the polar springtime (Wayne, 1991). The very low temperatures of the Antarctic stratosphere create ice clouds called polar stratospheric clouds (PSCs). Also in 1986, Michael B. McElroy and colleagues described a role for bromine in ozone-depleting reactions. The ice crystals that make up these PSCs are where heterogeneous photo-chemical destruction of ozone take place. Chlorine chemistry. Caldeira, 2008]. . During the cold dark Antarctic winter, stratospheric ice clouds (PSCs, polar stratospheric clouds) form when temperatures drop below -78C. One main type of PSC is made up mostly of supercooled droplets of water and nitric acid and is implicated in the formation of ozone holes. Schoeberl MR, Hartmann DL. Polar stratospheric clouds (PSCs) play a central role in the formation of the ozone hole in the Antarctic and Arctic. However, another feature of the polar vortex helps explain the discrepancy between model predictions and actual ozone depletion. This study examines the properties of polar stratospheric clouds (PSCs). The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. (Sweden, January 2000; from NASA website) ESS11 Prof. Jin-Yi Yu How PSCs Affect Ozone Hole!The ice crystals in the polar stratospheric clouds provide surface for the ozone depletion surface to occur more easily. Ozone depletion has also been associated with an observed seasonal poleward expansion of the Hadley cell [Hu and Fu, 2007]. In contrast, the Earth’s surface in the northern polar region lacks the land/ocean symmetry characteristic of the southern polar area. Much larger decrease in stratospheric ozone is observed around Earth’s polar regions. ODS are broken down by sunlight in the stratosphere, producing halogen (e.g. Recent aircraft missions have In the polar regions, heterogeneous reactions on polar strato- spheric clouds (PSCs) result in the annual formation of the ozone hole during the southern hemisphere spring [Solomon, 1990]. Satellite-based instruments have been monitoring these clouds long before the discovery of the ozone hole by observing the attenuation of sun light, which is scattered at wavelengths characteristic of the size of the cloud … The thinning or reduction of Ozone depletion is most prominent in the Polar Regions, especially over Antarctica. ANSWER: (a) 71. Special reactions that occur on PSCs, combined with the isolation of polar stratospheric air in the polar vortex, allow chlorine and bromine reactions to produce the ozone hole in Antarctic springtime. After some of the first observations of PSCs by McCormick et al. chlorine or bromine) atoms, which subsequently destroy ozone through a complex catalytic cycle. Based on her expertise in modeling atmospheric chemistry and air movements, Solomon suspected that some unknown chemical processes involving CFCs or CFC products were causing these losses. Prather, M.J., 1992: More rapid polar ozone depletion through the reaction of HOCl with HCI on polar stratospheric clouds. Polar Stratospheric clouds • Polar winter formation • Have polar vortex • Isolated air mass • Nitrogen oxides held in clouds as nitric acid •NO 3 particles grow and fall out • Facilitates ozone … 1. Emissions of ozone-depleting substances by the United States have been significant throughout the history of the ozone depletion issue. Stratospheric ozone is constantly being created and destroyed through natural cycles. Most of the available chlorine (HCl and ClONO2) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl2O2 throughout the Arctic polar vortex before midwinter. research is to study stratospheric ozone depletion in polar regions. The severe depletion of the Ozone layer in any particular area is called Ozone Hole. Polar ozone depletion is linked to chemical reactions taking place within polar stratospheric clouds, which occur in the stratosphere when the temperature drops below a threshold value. Temperatures in the lower stratosphere are closely coupled to ozone through dynamics and photochemistry. Ground-based and in situ monitoring of polar stratospheric clouds. » Serial entrepreneur Waqar Azmi has launched Smart Business Box to help startups and SMEs fight the Covid-19 pandemic » Bradman in making in this Kerala backyard However, because it gets very cold above the S. Pole in the winter, polar stratospheric clouds do sometimes form (they are made from water and other materials). Antarctica) are: (2) The presence of POLAR STRATOSPHERIC ICE CLOUDS -- on the surfaces of these extremely cold cloud particles certain chemical reactions are more efficient and faster. Dramatic springtime depletions of ozone in polar regions require that polar stratospheric air has a high degree of dynamical isolation and extremely cold temperatures nec- essary for the formation of polar stratospheric clouds. The polar stratospheric cooling that is a consequence of ozone depletion is largest during austral spring (September-October-November), following the season of maximum ozone depletion [e.g., Previdi and The polar stratospheric clouds in Antarctica are only formed when there are very low temperatures, as low as −80 °C, and early spring conditions. The depletion was confined to the spring months (September-November); no depletion was observed in other seasons. A significant decline in ozone over the Arctic last winter was due to an increase in the area and longevity of polar stratospheric clouds (PSCs), according to a group of researchers who participated in a large, international atmospheric science campaign. Nature , 355 , 534-537, doi:10.1038/355534a0. PSCs enhance the production and lifetime of reactive chlorine, leading to ozone depletion … RELEASE: 00-43AR. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. Stratospheric temperatures fall below –88°C. The winds thus acted like a barrier, preventing ozone from other parts of the atmosphere from replenishing the low ozone levels over the Arctic. These reactions lead to the production of free radicals of chlorine in the stratosphere which directly destroy ozone molecules.
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