Ice halos are rings, arcs and bright spots that appear when sunlight passes through tiny hexagonal ice crystals in thin, high cloud. The most common is the 22° halo, a ring 22 degrees from the sun. Others, such as sun dogs, the circumzenithal arc or the parhelic circle, depend on how the crystals are shaped and how they fall.

This camera looks straight up through a fisheye lens and sees the whole sky at once. A small black disk on an arm blocks the direct sun so the faint halo light around it is not drowned out. The whole camera turns with the sun through the day, which is why the sun always sits just below the centre of the picture while the compass slowly rotates around the edge.

Every half minute the camera averages a burst of short exposures into one clean frame. The live view shows the newest frame, and the reference rings mark where each halo would appear for the sun's current position.