11 January, 1999

11 January

Pole Temp.:

min. -28.4 F

max. -21.7 F

F=1.8C+32

Wind Chill -35

HALO THERE!

Today at Pole we were treated to a most spectacular display in the atmosphere. The sun shone through a shower of ice crystals that rained down from the clouds above to produce a combination of sun halos, sun dogs (the Fins call them side suns) arcs and circles that is believed to have never occurred simultaneously before.

Two of the nicest people at Pole, Marko Riikonen and Jarmo Moilanen, both of Finland, just happen to be two of the best authorities on the formation of the phenomena we witnessed in the sky this afternoon. They explained that the shapes of the falling ice crystals, as well

as their orientation to the sun's light as they fall, create the different effects that we see.

CRYSTAL SHAPE VISUAL PHENOMENA

Plate Sun dogs, Circles, Circumzenith arcs

Single Oriented Tangent arcs,

Column Infralateral arcs, Anthelic arcs

Double Oriented Parry arcs, Tape's arcs,

Column Hastings arcs, Parhelic circles, subanthelic arcs

Equidimensional 22 degree, 46 degree Randomly Oriented Halos

Pyramidal Multiple Halos

The effects that were seen in the sky at Pole were simulated in a labeled drawing by Jarmo and are included with the pictures below. Please also visit his website for additional information on this magnificent display at http://www.netppl.fi/~jarmom/index.htm

Marko and Jarmo provided drawings of the types of crystal that formed the halos, sun dogs, arcs and circles.

This is beautiful computer simulation based on ice crystal data depicts the sky the way it appeared for at least thirty minutes.

A is TEA enjoying the awesome beauty of where she is. (Photo Lisa Beal)

Pictured from the top: Circumzenith arc; Parry arc; Twenty-two degree upper tangent arc; Twenty-two degree halo; The speckles are falling ice crystals.

Jarmo's meticulously labelled sketch of the sky has each effect numbered.

The list was long.

There were more.

Pictured from left to right at the Halo Shack are: Elke Bergholtz, Sue Bowman, Marko Riikonen, Jarmo Moilanen. Inside the shack, our friends analyzed the sizes and shapes of the crystals that were captured during the display. They videotaped the atmospheric event in its entirety.