Upper sun pillar over Bear Creek at County II in western Portage County, Wisconsin.

An upper Sun pillar is an atmospheric optical phenomenon that appears as a vertical column of light extending upward from the Sun. The reflection and refraction of sunlight by ice crystals in the atmosphere can produce sun pillars when the conditions are right. 

The size, shape, and orientation of the ice crystals determine the appearance of the pillar, including its length, width, and color. Conditions produce sun pillars 20 to 30 times a year in central Wisconsin. They typically occur in the morning when the air is very still.

When the Sun is low on the horizon, the air is still, and plate-like ice crystals are gently falling from the sky; light can reflect and refract through the crystals as they travel to our eyes. The reflected light appears as a column extending above the Sun.

You can spot an upper Sun pillar 30 to 60 min before sunrise. If you watch it for a while, it will creep southwards following the Sun’s movement below the horizon.

Look for sun pillars near sunrise or sunset on cold days when the air is still.  Once you look for them, you will see them more often and will also begin to notice halos.