Air is reasonably soluble in cold water, less suable in warmer water and very low in ice. It is common for a black ice sheet to form shallow puddles on a warm afternoon and for them to get a thin layer of ice to form to form on their surface. As the water freezes the dissolved air is precipitated as air bubbles. The patterns can be spectacular.
Above: Two inch new black ice near Port Henrey NY. Scale: a foot or two
Bubble: about 1:1 scale
Above: Bubbles , about 1:1 scale.
The above picture is (I think) a complex drain feature. The scale is the image is about hald size.
A focus stacking camera like the Olympus TG-6 helps a lot. A black camera is better than a red one.
