Spectacular 'rainbow clouds' light up northern skies in a rare skywatching treat (photos)

Nacreous clouds also known as polar stratospheric clouds have been appearing across northern skies. We've rounded up some of the best photos of these rare 'rainbow clouds'.

Spectacular 'rainbow clouds' light up northern skies in a rare skywatching treat (photos)
Nacreous clouds also known as polar stratospheric clouds have been appearing across northern skies. We've rounded up some of the best photos of these rare 'rainbow clouds'.