  The intensive polar stratospheric vortex in the Arctic that shifted to
northern Europe in the winter of 2019-2020 caused low temperatures and the
frequent occurrence of polar stratospheric clouds followed by a significant
decrease in the total ozone content. Polarimetry and multi-color photometry
using all-sky cameras in Lovozero (Murmansk Region, Russia, 68.0 deg N, 35.1
deg E) together with a new method of cloud field separation against the
twilight background allowed for finding the light scattering characteristics
related to the particle size distribution of polar stratospheric clouds. The
results are compared with lidar and balloon experiments. The conditions of the
appearance of visually bright polar stratospheric clouds of type I are
discussed.
