Created on August 13, 1999
Last updated on August 15, 1999
I hadn't heard about sun pillar phenomenon when I saw the sight of the picture at the first time. There seems a bulk of light shaped like a pillar floating in the air, directly below the position of the sun. I tried to explain how this phenomenon can occur by myself. Later, I found my guess was right and it is called sun pillar. I'm now showing the pictures and make some explanation.
On paticular atmospheric conditions, very small crystals of ice floats in the air like mist. In some occasion, it is called diamond dust. Crystals can be in different shapes. Sun pillar can be seen when the shape of crystal is thin and flat plate.
Most flat plates of ice in the air are almost parallel to the ground surface. It means there are many small mirrors in the air parallel to the ground. Those in straight position between sun and observer reflect light from the sun, and makes sun pillar. This is somewhat similar to the reflection from sea surface on sunset or sunrize.
On this picture, sun pillar is below the sun, because observer is looking down to the valley where ice crystals exists. Usually, sun pillar can be seen above the sun which is below the horizon, or above bright lights on the ground far away.
Following links might help.
The next picture is a little bit complicated. There is an arc colored like a
rainbow. Below that, a straight thing that is also colored like a rainbow.
Sun pillar is not the only phenomenon produced by ice crystal particles in the air. Circular halo is the one of popular things. While rainbow is on the other side of the sun, circular halo can be seen just around the sun. Those things are not made by reflection as sun pillar but refraction. Therefore they are colored by the principle of prism.
Imagine there are the sun and sun pillar on the right side of this picture,
just like the first picture. The arc on the upper half of the picrure is a
part of circular halo. The straight thing on the lower half is a halo whose
light source is the sun pillar. This is not circular because the light source
is not a single point like the sun, but a form of pillar.
All Konica Big mini BM-201 + Konica Qscan 1200dpi 1:2