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 | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Hay Jones, David |
Taille de l’image : | 4630 px × 3036 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |