Peru Rainforest Halos

Stunningly bright halos captured by Phil Torres for and Steve Gettle (Wilderness Images).

Tambopata River near the Tambopata Research Center, Peru, Sept 23, ‘12. 

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Images refuting the myth that magnificent ice halo displays are only the stuff of Polar regions or at least very cold weather.     These, over the tropical rainforests of Peru were in high and icy cold cirrus cloud which occurs anywhere on the planet.

The sun was ~72° high and the halos therefore differ from their more familiar temperate climate aspect.   The sharply coloured ring around the sun is a circumscribed halo generated by column crystals drifting with their long axes almost horizontal.   At high sun the halo is nearly circular but there are traces of the truly circular 22° halo (from randomly oriented crystals) within it.

The smaller white ring through the sun is a diminutive version of the normally huge parhelic circle. It is formed by column and plate shaped crystals. A rarity is the Wegener arc looping through the parhelic circle.   Not often so bright or extensive.   More halos were beneath the sun.  Scroll down for these and the labelled HaloSim computer ray tracing.

Close-up of the brightly coloured circumscribed halo.

When the sun is high this is often mistaken for the common 22° circular halo but the latter's colours are less saturated and slightly more widely spread.

Below the sun are two huge coloured arcs. The lower one, always parallel to the horizon, is a circumhorizon arc formed by sun rays passing through plate shaped ice crystals.,

Curving upwards from the circumhorizon arc is a rarer halo, a high-sun infralateral arc formed by rays passing between the end and side faces of horizontal column crystals.

See the simulation below for identification.
A HaloSim computer ray tracing of the display. The program traces millions of rays through mathematical representations of cloud ice crystals.