A sun ring (a.k.a., a 22-degree halo) forms an halo around a palm tree. Some refer to these as sun dogs but that is only true if bright spots (the ‘dogs’) appear on the ring usually to the left and right. Both form when sunlight refracts off ice crystals high in the sky to produce a rainbow like ring. They are often a harbringer of rain (and indeed, today, a day later, it has rained).
(And this ring appears to be atop the palm, so it is my entry for this week’s Photo Challenge.)