What is "moonbows"

Usage examples of "moonbows".

They still hung above the moon-misty drop, the moonbows still made their slow and dreamlike revolutions before the cur­tain of endlessly falling water, the wet and brutal stone faces of the dog-guardians continued to jut out of the torrent, but that world-ending thunder was gone.

They are inside the wizard's glass, they are inside the pink storm (those pink halos revolving around the light fixtures re­mind Jake of The Falls of the Hounds, and the moonbows revolving in the mist), and this is happening all over again.