Sun Halos and Sun Dogs:
(click here to see pictures of the Fairbanks sun halo event of 6 March 2002!)


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.

Finally, this picture clearly shows what I think is a "circumzenithal arc" (see the computer-generated picture above). I don't think conditions were right for halos to form except where the arc is visible because none of the usual other features is present. The arc at top can't be a rainbow since it bends the wrong way....




Sun Dogs:
    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.






 
Sun Pillars:

A Sun pillar and sun dog in Fairbanks. The steam plumes are from houses and the Alaska Range is in the distance.This is as high as the Sun gets in late January in Fairbanks.


Here is a pillar pointing the other way.


Another sun pillar & sun dog over Fairbanks.


Here's a double (up AND down) sun pillar.

Sun pillars are the result of the suspension of tiny ice crystals in the air, which form mostly in extreme cold conditions, shaped like either hexagonal plates or rods (see the computer-generated image above and the link associated with it). When they appear the effect is like invisible glitter in the air, which gives effect its' name: "diamond dust". When the crystals are plate-shaped they tend to 'float' with their large planes facing up and down. Sun pillars are the reflection of the Sun off these crystal faces.

Here're a few more:                 (click for bigger).



The end.