A simple halo over LaFayette/Old Mill at UVM. Whenever sun halos form, the "22-degree halo", shown here, is almost always the first thing to form and easiest to see.
The rest of the pictures on this page are from Alaska. For this halo (above) I used the UAF Natural Sciences building to block the Sun...
...and here I used the IARC building.
This is a computer generated theoretical picture showing some of the less rare solar atmospheric optics features and the ice crystal types that cause them. It was generated by a program called HALOS (natch...), which is available for download at http://www.sundog.clara.co.uk/halo/crystals.htm which is an excellent site for anyone who wants to know more about halos and other optical effects.
These pictures (above, below) are of the same event. In the image above "tangent arcs" are visible at upper right and left center. In the lower picture a true sun dog (parhelion) is visible and a "parhelic arc" extends from it to the right and faintly to the left. Compare these to the computer generated image above.
A good image of a true sun dog.
Well, strictly speaking the pictures below are not true "sun dogs" (see above). They are more akin to the "22-degree halo", but they are formed in ground level ice crystals (ice fog) not in crystals high in the atmosphere. But most people call these things sun dogs too, and around here they are fairly common.
Sun dogs over west Fairbanks, taken from the West Ridge area of UAF at around noon, a few days
after Winter solstice.
Here is a sun dog formed in a bank of ice fog. Ice fog is a fog that forms as ice crystals instead of water droplets. In Fairbanks it often forms when there is a temperature inversion holding polluted air in place and temperatures are below zero, Fahrenheit. Car exhausts then supply a lot of the water vapor for ice fog. To see some other effects of inversions, see the "Mirages" and "Other Stuff" links, one page back.
Here is a pillar pointing the other way.
Another sun pillar & sun dog over Fairbanks.
Here's a double (up AND down) sun pillar.