Diamond dust ski halo's:

Ski resorts are some of the best places to see sun halos--rings and pillars of light that surround the sun when ice crystals fill the air. The most sublime halos are caused by jewel-like crystals called "diamond dust." On Dec. 7th, Kameron Barge was skiing in Whitefish, Montana, when he saw these specimens:


©Kameron Barge

"As we rode the chair down into the clouds today, we begin seeing all sorts of halos, and sundogs!" says Barge. "It was an unforgettable display."

Ordinary sun halos are caused by ice crystals floating in high cirrus clouds. "Ski halos," on the other hand, are formed by ice crystals near the ground, kicked into the air by the action of skis and snow-making machines. A close look at Barge's picture shows specks of light in the air. Those are the glittering crystals of diamond dust which make these halos so beautiful.

Barge documented a rare variety of forms: a 22-degree halo, sundogs, sub-sundogs, a sub-sun, a lower sun pillar, an upper tangent arc, a 46-degree halo, a circumzenithal arc, and a partial parhelic circle--all sculpted from sunlight by floating diamond dust.

If you're on the slopes this weekend, and the sun dips behind a cloud of ice, be alert for "ski halos." They can make your day.
Bron: http://www.spaceweather.com/