Polar stratospheric clouds over silhouetted trees at sunset. These are the nacreous or mother-of- pearl type of polar stratospheric cloud (PSC). PSCs

---

Polar stratospheric clouds over silhouetted trees at sunset. These are the nacreous or mother-of- pearl type of polar stratospheric cloud (PSC). PSCs are high-altitude icy clouds that are found in the polar stratosphere at heights of about 24 kilometres. They only form during winter when the temperature drops below around -80 degrees Celsius. PSCs play a key role in the destruction of ozone by chlorine. They convert harmless forms of chlorine into highly-reactive forms. Chlorine is carried into the stratosphere in CFCs (chlorofluorocarbons), gases used as refrigerants and during foam plastic manufacture. Photographed over Swedish Lapland.

---

Size: 3213px × 4432px
Photo credit: © DAVID HAY JONES/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: apostle, apostles, australia, australian, campbell, coast, coastal, coastline, coastlines, coasts, earth, eroded, erosion, formation, formations, geographical, geography, geological, geology, limestone, national, ocean, park, parks, pillar, pillars, port, rock, rocks, rocky, scenery, sciences, sea, sedimentary, shore, shores, stack, stacks, twelve, water