vibe.io on Instagram: "Polar stratospheric clouds (PSCs), often called nacreous or “mother-of-pearl” clouds, develop high in the winter polar stratosphere, roughly 15–25 kilometers above Earth. They appear only when the air is bitterly cold—around −78 °C or even lower. Unlike ordinary clouds, PSCs consist of ice crystals mixed with super-cooled droplets of water and nitric acid. These clouds are important in ozone depletion because their surfaces trigger chemical reactions that release chlorine