Home   OPOD   What's New    Rays & Shadows   Water Droplets   Rainbows   Ice Halos     Contents     Crystals     Frequent Halos     Infrequent Halos       Why infrequent?       46° Halo        Supra/infralateral       Parry Arcs       Lowitz Arcs       Moilanen Arc       Kern Arc       120° Parhelia       44° Parhelia       Subhorizon Arcs         Subsun          Subparhelia         Antisolar Arcs        Pyramidal     Multiple Displays     Other Worlds     Observing Halos     HaloSim   High Atmosphere   Links & Resources   Search - Index   123456789012345678		Subhorizon arcs
		Halos beneath the sky. A subsun, sub parhelia, subparhelic circle and a subcircumzenithal arc shine below the horizon. Continuations of 'ordinary' arcs go beneath the horizon also. Fisheye simulation centered on the horizon, sun 10� high. Imagine a halo display mirrored in a lake. Subhorizon halos are similarly formed except that the mirroring is inside the very crystal making the halo. An extra reflection from a lower horizontal face produces the subhorizon counterpart of an ordinary plate crystal halo. No multiple scattering or reflection by separate crystals is needed. Subtleties of the refraction and ray paths make subhorizon arcs very similar to but not identical to their above horizon counterparts. Look for subhorizon halos from aircraft, hills or mountains. Sometimes they can even be seen in snow and ground frosts.

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