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       Pyramidal         Circular Halos            9° halo         Parhelia     Multiple Displays     Other Worlds     Observing Halos     HaloSim   High Atmosphere   Links & Resources   Search - Index   123456789012345678		9� Circular Halo
		A fine 9� halo imaged by Harald Edens in the Netherlands. A faint 18� is also visible inside the bright outer halo. �Harald Edens, reproduced with permission.      The innermost of the odd radius halos forms when pyramidal crystals have a central prism section. Sunlight passes between a central face and an opposite pyramidal face. These faces are inclined at only 28� and the corresponding minimum deviation for rays passing through them is 9�.  When the crystals are poorly aligned - as they usually are - then a circular halo forms.

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