"Sun dogs" result from an atmospheric effect that appears only when the air is really, really cold. I shot this on a morning in Fairbanks, Alaska when the temperature outside was 25 degrees below zero Fahrenheit.
While I was in the frozen North, I took the opportunity to check out some of the snowflakes in greater detail. Fortunately I had brought my microscope!
They say that no two snowflakes are exactly alike. But upon closer inspection—they're right! These are just a few of the myriad amazing shapes I've seen in the wild recently.