22º halo image index
Pole 4th January 1999. The South
Pole is famed for its diamond dust
halo displays but this 22-degree halo is in cirrus cloud. Photographed
by Marko Riikonen.
Note the special purpose sun shield. Crossed polarising filters at
its tip let through just enough light to show the disk of the sun
enabling precise measurements of the size of halos. Image
©Marko Riikonen, shown with permission.