Sun Halo at Winter Solstice
Sometimes it looks like the Sun is being viewed through a large
lens.
In the above case, however, there are actually millions of lenses:
ice crystals.
As water freezes in the upper
atmosphere, small, flat, six-sided, ice crystals might be formed.
As these crystals flutter to the ground, much time is spent
with their faces flat, parallel to the ground.
An observer may pass through the same plane as
many of the falling ice crystals near sunrise or sunset.
During this alignment, each crystal can act like a miniature lens,
refracting sunlight into our view and creating
phenomena like parhelia, the technical term for
sundogs.
The above image was taken in the morning of the 2000
Winter Solstice near Ames,
Iowa,
USA.
Visible in the image center is the Sun, while two bright
sundogs glow
prominently from both the left and the right.
Also visible behind neighborhood houses and trees are the
22 degree halo, three
sun pillars, and the
upper tangent arc, all created by
sunlight reflecting off of atmospheric ice crystals.