Ukrainian researchers at the Academician Vernadsky station have captured a rare atmospheric phenomenon over Antarctica—nacreous clouds, which seldom grace the polar skies.
The National Antarctic Scientific Center shared the images on its Facebook page. Scientists emphasized that the formation of such clouds requires very specific conditions, making each sighting valuable for studying stratospheric processes.
As Anzhelika Ganchuk, head of the 31st Ukrainian Antarctic Expedition, explained, most common clouds form in the troposphere—the lower, moist layer of the atmosphere. Nacreous clouds, however, emerge higher up in the stratosphere at altitudes of 15–30 kilometers, where the air is almost dry.
The first requirement is the transport of moist air into the stratosphere. This occurs during powerful tropospheric cyclones or through mountain waves: airflow hits a ridge, rises, passes over it, and descends, with the wave crest reaching into the stratosphere.
The second requirement is extremely low temperatures of minus 50 degrees Celsius or lower. Under these conditions, moisture rapidly transforms into ice crystals or tiny supercooled droplets, while strong winds help to disperse them.
The third condition is the sun. Its rays reflect off the crystals to create an iridescent, rainbow-like optical effect. For this to occur, the sun must be positioned just a few degrees below the horizon—at sunrise or sunset. During the day, under scattered light, these thin clouds appear almost colorless.
Anzhelika Ganchuk noted that nacreous clouds have become one of her favorite phenomena and were even featured on the expedition team's official patch. According to her, they are not only a unique example of atmospheric processes but also something truly magical to the human eye.
Observations at the Academician Vernadsky station provide a better understanding of how stratospheric clouds form in polar latitudes and the factors that influence their appearance.
Such records help track rare atmospheric phenomena in the world's most remote regions.