Ice Crystal Halos

Lascar display

Lascar display

This was seen on 27 November 1997 in Chile, on the foot of Lascar volcano, where Leena Virta and I photographed it. The image – that is stacked from nine slides – presents only one stage of the display. The photos were taken in 10 minutes interval, during which sun elevation change was from 25.5° to 23.5°.

The display contained some exotic halos, such as 28° halo. There seem to be also traditional pyramidal crystal halos, in this image 23° plate arc and pyramidal helic arc. However, what looks as 18° plate arcs are actually below the level of the sun (this was pointed out by Walt Tape years ago).

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