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| Diamond Dust Sundog & Pillar |  |
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| A
rainbow fragment suspended in front of distant trees? No, the lower
right picture reveals that it is a sundog. It was well below freezing when David van Unen (more of his images) captured this halo shortly before sunset on January 21, 2003 at Fort St. John, B.C., Canada. The sundog was formed not by crystals high in cirrus cloud but by ice crystals called "diamond dust" floating nearby and in front of the trees. A sundog so tall must have been formed by plate-like crystals which wobbled substantially. The simulation at bottom right shows that some of their tilts were at least ±6° from horizontal. The dust also formed a sun pillar and subsun ~ photo ~ in which individual glittering crystals were visible. The close up below shows ice crystals floating within a few feet of the camera. Ignore the spikes radiating from the sun, they are the camera lens flare. Photos ©2003 David J van Unen, shown with permission. |
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| Diamond dust ice crystals glitter within a few feet of the camera to make a lower sun pillar which merges imperceptibly into a vertically elongated subsun. |
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