A special natural phenomenon over the UK: rare mother-of-pearl clouds cloud the sky | Science and the planet

Mother-of-pearl clouds are a special case. Unlike most clouds that sweep across our skies every day, this rare natural phenomenon is not found in the troposphere, but much higher in the stratosphere. About 25 km to be exact. This is why they are sometimes called polar stratospheric clouds.

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Mother-of-pearl clouds look as if someone has painted the sky with a brush of beautiful and bright pastel shades. This is because they are made up of tiny ice particles, one-hundredth of a millimeter in size. They contain water, nitric or sulfuric acid and are formed at very low temperatures of about -85°C. When sunlight shines on these crystals from below, mesmerizing iridescent colors appear. It is therefore best seen during twilight when the sun is a few degrees below the horizon. At that time, the normal high clouds were completely gray and you could clearly see the difference. The seashell cloud’s wave appearance is due to air currents in the stratosphere.

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You mainly see pearlescent clouds in the polar regions during winter periods because they only occur in extremely low temperatures. Normally, the air mass also stays well in place, and mother-of-pearl clouds are reserved for the poles and northern regions such as Scandinavia, Greenland, Alaska, Scotland, and parts of Russia. But circulation is disrupted, causing a bubble of cold polar air in the stratosphere to suddenly move south. This can not only provide a picture of the winter weather, but also provide an opportunity to discover this beautiful weather phenomenon.