Subsuns can be unbelievably bright. They are a direct reflection of the sun by millions of tiny mirrors. Each mirror is the upper or lower face of an hexagonal plate crystal. The crystals, in this case drifting in the nearby -20 Celsius air, are aligned by drag forces with their large faces nearly horizontal.
Some larger crystals wobble a few degrees from horizontal. Reflections from them form the sun pillar extending from the subsun up to the sun.
Rays refracted between to near vertical side faces of the same plate crystals formed the sundog at lower right. The blue glow lower down is a lens reflection.
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