clouds/National Antarctic Science Center
Members of the 29th expedition to the Antarctic station “Akademik Vernadskyi” shared a video of a rare phenomenon – nacreous clouds that occur mostly in winter.
On the video , published by the National Antarctic Science Center, clouds of an unusual shape and color can be seen against the background of the Sun, part of which is hidden behind the horizon.
Do you know what color “patches” are in the sky? This is a rather rare phenomenon – nacreous clouds. In the Antarctic, they can be observed literally several times during the year of the expedition, mainly in winter, the National Antarctic Center said.
The scientists reminded that it is now winter in the Southern Hemisphere and explained how nature “paints” such beautiful landscapes. .
Most clouds live in the lower layer of the atmosphere – the “moist” troposphere. But mother-of-pearl is formed in the next layer – the “dry” stratosphere. Moisture is carried there by a strong flow of air: usually it hits a high mountain range, “goes” up, goes around it and “falls” down. The top of the wave passes through the lower part of the stratosphere, located at an altitude of 15-30 km. It may also be connected with strong tropospheric cyclones, scientists say.
It is said that when the flow enters the stratosphere, there must be abnormally low temperatures (about -85°C) for the moisture to turn into ice crystals. This whole process must be illuminated by the sun, which is a few degrees below the horizon, that is, rising or setting.
It is then that the light is reflected from crystals in the clouds so that the optical effect of iridescence occurs. It just “paints” the clouds in different colors. When the sun rises higher, they are almost invisible against the background of scattered light, because they are very thin.
Since clouds consist of ice crystals, are observed mostly in the polar regions and are formed in the stratosphere, then their official name is icy polar stratospheric clouds. And because of their colorfulness, they were called mother-of-pearl, the scientists explained.