Moon, the patter of air molecules and ice crystals unite to scribe geometric arcs on the sky.
Water vapour molecules speed and collide randomly. When air cools the molecules slow, stick together to form ice. Not in a jumbled way. In a highly ordered geometric lattice of endless hexagons. Which beget hexagonal crystals. Which refract light, glint.
Disorder again. Crystals drift downwards. Untold millions of impacts with air molecules twist and pull to align them almost perfectly.
Sky scribings from disorder.Image ©Roger Benoit, shown with permission