Students of the Earth to Sky Calculus project were in the Arctic Circle on January 22, preparing to launch balloons to study cosmic radiation. A few minutes before the start, polar stratospheric clouds began to appear in the sky, and the group hastened to launch two balloons into the very heart of the outbreak.
Polar stratospheric clouds are very rare. They form in the stratosphere only at temperatures of -85 ° C. The balloons with the help of cameras recorded a video of the clouds from a height of 23 km. According to scientists, this is the first time that nacreous clouds have been captured directly from their habitat - the stratosphere. The footage shows fibrous structures that cannot be seen from the ground.
The polar stratospheric vortex, a small area filled with cold air, which forms in the troposphere and stratosphere over the Arctic due to cooling in the cold half of the year, helped to deliver balloons to the stratosphere. Shortly before launch, something strange happened with the polar vortex: it became elliptical and rotated, splashing out a mass of cold stratospheric air over northern regions of Scandinavia.
What the vortex looked like on January 22-23 can be seen in data obtained by NASA's Microwave Limb Sounder (MLS) instrument. Note the purple blob over northern Sweden. This is cold air. Polar stratospheric clouds can form inside an area with a white outline.
Polar stratospheric clouds are rightfully considered the most beautiful clouds on Earth. They are made up of tiny ice crystals that scatter high-altitude sunlight and make them sparkle with bright colors like daylight.
Photos of Earth to Sky student Jordan Herbst from January 22-23 show what the clouds looked like from the ground. Now we know that they are no less beautiful from within the stratosphere.