Picture taken 25/08/2009 15.40 - McMurdo Antarctica. Feb 10, 2011. Polar stratospheric clouds (PSCs) play a central role in the formation of the ozone hole in the Antarctic and Arctic. The stratosphere is very dry; unlike the troposphere, it rarely allows clouds to form. Observations of Antarctic Polar Stratospheric Clouds by GLAS Stephen P. Palm Michael Fromm Jim Spinhirne Polar Stratospheric Clouds (PSCs) frequently occur in the polar regions during winter and are important because they play a role in the destruction of stratospheric ozone. Because of the very low temperatures required, nacreous clouds are usually only visible from the UK when the cold air which circulates around polar regions in the stratosphere (known as the stratospheric polar vortex) is displaced and hovers temporarily over the UK. Nacreous Clouds (Type II Polar Stratospheric Clouds) Nacreous Clouds over Antarctica Imaged by Cherie Ude at McMurdo Base in 2004. Department of Agriculture, Water and the Environment. In fact, it is estimated that just one atom of chlorine in the stratosphere can destroy over 100,000 ozone molecules. These reactions lead to the production of free radicals of chlorine in the stratosphere which directly destroy ozone molecules. The large surface areas of these cloud particles provide sites for chemical reactions to take place. Cold temperature enables the stratospheric clouds to form. Polar Stratospheric Clouds. This type of PSC is also referred to as nacreous (/ˈneɪkriəs/, from nacre, or mother of pearl, due to its iridescence). PSCs provide surfaces upon which heterogeneous chemical reactions take place. Hence, at this time the polar stratospheric clouds tend to form. Temperatures hover around or below -80'C for much of the winter and the extremely low antarctic temperatures cause cloud formation in the relatively ''dry''stratosphere. Polar stratospheric cloud The stratosphere is very dry; unlike the troposphere, it rarely allows clouds to form. The payload captured first-ever images of the clouds from their own habitat--the stratosphere. But in the long months of polar darkness over Antarctica in the winter, atmospheric conditions are unusual. Nacreous clouds (Type II PSCs) glow brightly with vivid iridescent colours. Observed from the ground, this phenomenon is known as noctilucent clouds. When south polar spring arrives (Aug-Sept), UV radiation from the Sun reaches the Antarctic Circle and reacts with the stratospheric clouds. The following list highlights the characteristics and facts of the stratosphere in more detail. Polar stratospheric clouds (PSCs), also known as nacreous clouds from nacre, or mother of pearl, due to their iridescence, are clouds in the winter polar stratosphere. The visibility of the colors may be enhanced with a polarising filter. These reactions lead to the formation of large amounts of reactive chlorine and, ultimately, to the destruction of ozone in the stratosphere. Despite two decades of research, the climatology of PSCs is not well described, and this impacts on the accuracy of ozone depletion models. Forward-scattering of sunlight within the clouds produces a pearly-white appearance. The severe depletion of stratospheric ozone in late winter and early spring in the Absorption cross sec-tions and rate coefficients are taken from recent JPL recom-mendations (Sander et al.,2011). However, the true 'upper class' of the clouds are the rare noctilucent (left) or polar stratospheric clouds, … Polar stratospheric clouds (PSCs) are some-times present in the stratosphere at alti-tudes between 20 and 30 kilometres. Upon the return of sunlight to the polar caps in spring, chlorine takes part in ozone-destroying catalytic cycles. The particles grow from the condensation of water and nitric acid (HNO 3). The clouds are classified into Types I and II according to their particle size and formation temperature. We pay our respects to their Elders past, present and emerging. Polar stratospheric clouds (PSCs) are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 m (49,000–82,000 ft). Polar Stratospheric Cloud Background These clouds exist at very high altitude (~70,000 ft) within Earth's stratosphere. Nacreous Clouds or Polar Stratospheric Clouds. Type Ia clouds consist of large, aspherical particles, consisting of nitric acid trihydrate (NAT). In the extremely low temperatures of the polar stratosphere in winter, nitric acid and small traces of water vapor condense into clouds, primarily below 25 kilometers altitude. Due to their high altitude and the curvature of the surface of the Earth, these clouds will receive sunlight from below the horizon and reflect it to the ground, shining brightly well before dawn or after dusk. Polar stratospheric clouds (PSCs) and ozone Under normal atmospheric conditions, the two chemicals that store most atmospheric chlorine (hydrochloric acid, and chlorine nitrate) are stable. We acknowledge the Traditional Owners of country throughout Australia and recognise their continuing connection to land, waters and culture. More than a decade ago it was suggested that a cooling of stratospheric temperatures by 1 K or an increase of 1 ppmv of stratospheric water vapour could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud (PSC) particles. polar stratospheric clouds (Abbreviated PSC; also called nacreous clouds, mother-of-pearl clouds; rarely, luminous clouds.) The similarity here is clear with the inner surface of a mollusc shell such as an abalone for instance. ə s /, from nacre, or mother of pearl, due to its iridescence), are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 meters (49,000–82,000 ft). PSCs are wave clouds. Polar Stratospheric Clouds or nacreous clouds contain water, nitric acid and/or sulfuric acid. At the sub-Antarctic sites of Macquarie Island and Heard Island, stratospheric temperatures rarely reach the frost point during winter, but observations are still encouraged. Roll Cage Mary on the lower hill to the left. 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. Ozone holes are caused by chemical reactions that take place primarily on the surface of polar stratospheric clouds, ice particles, or liquid droplets, which form at high altitudes in the extreme cold of the polar regions. Polar stratospheric clouds (PSCs) form in the stratosphere at altitudes of 50,000–80,000 ft. CALIPSO spies polar stratospheric clouds. PSCs are very rare. The second problem with modeled denitrification shown in Figure 10 is that the HNO 3 at 63°S is about 1–3 ppbv smaller than the observed abundance from mid‐July until the end of the season. The winds thus acted like a barrier, preventing ozone from other parts of the atmosphere from replenishing the low ozone levels over the Arctic. At the sub-Antarctic sites of Macquarie Island and Heard Island, stratospheric temperatures rarely reach the frost point during winter, but observations are still encouraged. 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