When you look into the maze of bare branches of a forest in winter, you’re only seeing a fraction of the detail. The light illuminates only a few of these ice-covered branches. Most of them blend invisibly into the general gray.
Which of the smaller branches and twigs catch the highlights? Only those that are oriented 90 degrees to the direction of the light. The illuminated twigs align into concentric rings around the centerpoint of the light source; hence I’ve named the phenomenon “annular highlights.”
The three arrows in the photo are placed perpendicular to the illuminated twigs. If you follow the arrows, they lead to the location of the sun.
Annular highlights can also be observed in the scratches of a well-used stainless steel surface, like this cookie sheet and pot lid. Look for it in the window of a passenger train on a late afternoon, in a cobweb on a dewy morning, in a cornfield lit by a setting sun, or on telephone wires on a rainy night.