Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2020 January 10

                         Nacreous Clouds over Sweden
           Image Credit & Copyright: P-M Hedén (Clear Skies, TWAN)

   Explanation: Vivid and lustrous, wafting iridescent waves of color
   filled this mountain and skyscape near Tanndalen, Sweden on January 3.
   Known as nacreous clouds or mother-of-pearl clouds, they are rare. This
   northern winter season they have been making unforgettable appearances
   at high latitudes, though. A type of polar stratospheric cloud, they
   form when unusually cold temperatures in the usually cloudless lower
   stratosphere form ice crystals. Still sunlit at altitudes of around 15
   to 25 kilometers the clouds can diffract sunlight after sunset and
   before the dawn.

                       Tomorrow's picture: and beyond
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
                NASA Web Privacy Policy and Important Notices
                      A service of: ASD at NASA / GSFC
                             & Michigan Tech. U.

--- hpt/lnx 1.9.0