Then, there is the formation of Polar Stratospheric Clouds (PSCs). While the clouds look amazing, they can be potentially quite dangerous to our planet. The polar vortex and polar stratospheric clouds exist only over Antarctica, which is why the ozone "hole" exists only there. Polar stratospheric clouds (PSCs) are the exception. "A 'warm' polar stratosphere is typically in the temperature range -73 o to -63 o C. Of course, as soon as the wave has dissipated, the polar region begins to cool down again." The particles grow from the con-densation of water and nitric acid (HNO3). Polar stratospheric clouds (PSCs) are common in … Polar stratospheric clouds. PSCs appear in the lower stratosphere near the poles in winter. Lower average winter temperatures in the upper atmosphere might explain why nacreous clouds seem to be appearing with increased frequency and distribution. Polar mesospheric clouds (PMCs) are a diffuse scattering layer of water ice crystals near the summer polar mesopause. Although polar stratospheric clouds can form in the Arctic, they rarely last long enough for extensive decreases in ozone. Figure Q10-2. Meanwhile, chlorine concentrations build up during the polar winter, and consequent ozone destruction is greatest when the sunlight returns in polar winter . The nitric acid in polar stratospheric clouds reacts with chlorofluorocarbons to form chlorine, which catalyzes the photochemical destruction of ozone [3, 34]. Below: Dangerous beauty. This photo-graph of an Arctic polar stratospheric cloud (PSC) was taken from the ground at Kiruna, Sweden (67°N), on 27 January 2000. PSCs form during winters in the Arctic and Antarctic stratospheres. Description. The clouds Though nacreous clouds are officially known as "polar stratospheric clouds", they are now common over Scotland, and have been observed as far south as the Midlands. But the bigger the hole gets, the thinner the ozone layer will become over the rest of the earth. They are best observed during civil twilight, when the Sun is between 1 and 6 degrees below the horizon, as well as in winter and in more northerly latitudes. These are best observed during winters in more northerly latitudes. Polar stratospheric clouds create the conditions for drastic ozone destruction, providing … During the continuously dark polar winter, the air inside the polar vortices becomes extremely cold, a necessary condition for polar stratospheric cloud formation. Polar stratospheric clouds (PSCs) are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 m (49,000–82,000 ft). A polar winter vortex also forms in the Northern Hemisphere. This means more dangerous UV radiation will reach the Earth's surface. However, in general, it is neither as strong nor as cold as the one that forms in the Antarctic. Also known as nacreous clouds, these are the clouds that form in the winter polar stratosphere. 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