Prismatic ice rainbow, a rare phenomenon!
It asks for three conditions: high-altitude cirrus clouds, a sun at more than 58° above the horizon, and a parallel orientation of earth and the surfaces of ice particles in the cirrus.
( …more in the National Geographic article)
‘Diatom Rainbows’, a photomicrography by Michael Stringer; the rainbow-like effect is due to polarizing light-filters.
So very elegant!