Montana Halos
By James Perdue at Red Rock Lakes National Wildlife Refuge. "The only way to get here right now is a 28 mile snowmobile ride."
 ©James Perdue

About - Submit Optics Picture of the Day Galleries Previous Next Today Subscribe to Features on RSS Feed

The halos were formed by nearby diamond dust crystals.  

A 22° halo circles the sun, brighter towards the ground where the halo forming crystals were at their densest.    

A lower sun pillar stabs downwards from the sun and persists at the picture’s lower edge as individual glints from close-by crystals.

The brightenings outside the 22° halo to the left and right of the sun could be a due to a particularly dense band of crystals but they are more likely sundogs (parhelia) produced by plate crystals with large wobbles from horizontal.  

Look closely to see faint coloured ‘pillars’ extending downwards from each parhelion.

The HaloSim ray tracing simulation at left used randomly oriented crystals (for the 22° halo) and thin plate crystals with large wobbles from horizontal.    It shows the pillar-like extensions linking the parhelia to the below horizon subparhelia.