  The method of detection of light scattering on stratospheric aerosol
particles on the twilight sky background is considered. It is based on the data
on sky intensity and polarization in the solar vertical at zenith distances of
up to 50 deg from the sunset till the moment of the Sun depression to 8 deg
below the horizon. The measurements conducted in central Russia since 2011 had
shown the negative trend of stratospheric aerosol content, this can be related
with the relaxation of the stratosphere after the number of volcanic eruptions
during the first decade of XXI century.
