A sun pillar is a vertical column of light that appears above (and sometimes below) the sun when it sits low near the horizon. It is formed by sunlight reflecting off the near-horizontal faces of millions of tiny ice crystals — chiefly flat, horizontally-drifting plate crystals — acting like a field of tilted mirrors. The pillar is not a physical object but the collective glint from crystals along the vertical line between you and the sun.
Worth knowing
A sun pillar shows no rainbow colours because it is made by reflection, not refraction. Light simply mirrors off the crystals rather than splitting into a spectrum, so the pillar glows the same colour as the sun itself — often gold or fiery red at sunset.
Note
Still unsure it's the same cloud? Our app, Cloud Point— on iOS and Android — reads a photo and returns the likely type with altitude, useful when a formation is fading faster than you can look it up.
