Sundogs are a small rainbow near the sun: a small spectrum of light occasionally visible in the sky at the same altitude as the sun, either to the left or right of the sun and sometimes on both sides simultaneously They are a bright coloured spot on a parhelic circle, often seen in pairs and caused by ice crystals in the atmosphere diffracting light. [Mid-17th century. Via Latin from Greek parelion , from para "beside" + helios "sun".] Encarta® Reference Library 2004.

Now that winter is approaching (or has arrived) in the Northern Hemisphere, it seems an appropriate time to share information about this year round, but ice related phenomenon. These spots are caused by light refracted off ice crystals in our atmosphere. Sundogs are visible when the sun is near the horizon and on the same horizontal plane as the observer and the ice crystals. As sunlight passes through the ice crystals, it is bent 22 degrees before reaching our eyes. This bending of light results in the formation of a sundog. If the flat ice surfaces are horizontal to the viewer, s/he sees a sundog, but if the surfaces are random, a halo is seen.

Of course our forefathers interpreted these visual phenomena as signs from God. Once a miraculous sign was reported it was followed by an interpretation, which usually ended up appealing to the recipients or viewers to repent and do penance, and prayer to God for His mercy on the sinful people. This pattern was applied to all mysterious occurrences regardless of their individual nature; any inexplicable apparition was interpreted as a manifestation of God's wrath over the sins of the people. In the 17th century a variation developed concerning the interpretation of the different miraculous signs. Regarding celestial phenomena, there was finally an attempt to find a logical explanation for them. In 1626, for instance, Caspar Fuld suggested that a sundog indicated a weather change. Jacob Koppmayer in 1681, concluded that they generally predicted rain. Koppmayer even tried to make an attempt to give information about the natural cause of such apparitions. It is not astonishing, therefore, to find that our early forefathers carefully discriminated the various phenomena of sea and sky, and evolved terms, full of real meaning, which have been passed down to us through the generations, but now basically lack significance other than as items of weather lore.