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 and the sun dips behind a cloud of ice, be alert for "ski halos." They can make your day.