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Undertoad · 07-20-2005, 03:32 PM

Today's Earth Science Pic of the Day is breathtaking, an absolute stunner. At first I thought it must be enhanced, but no - as the official caption from photographer Thomas Herrmann has it:

Sitting in a garden in Erlensee, Germany on May 27, I realized that cirrus clouds were visible all across the sky. Knowing that these clouds can provide an opportunity to observe atmospheric phenomena, I kept an eye on the sky and was rewarded by seeing the amazing circumzenithal arc, shown above. With just a little imagination, you can see seahorses floating inside the arc. Circumzenithal arcs are perhaps the most colourful of all halo-related phenomena. In fact, many people who witness them believe they're rainbows because of their beauty and arc-like shape. However, contrary to a rainbow, which forms a circle around the antisolar point, a circumzenithal arc appears, as its name implies, at the zenith. Only the portion pointing towards the Sun is visible.

I still don't quite understand it.

07-20-2005, 03:32 PM	#1
Undertoad Radical Centrist Join Date: Jan 2001 Location: Cottage of Prussia Posts: 31,423	7/20/2005: Circumzenithal Arc Today's Earth Science Pic of the Day is breathtaking, an absolute stunner. At first I thought it must be enhanced, but no - as the official caption from photographer Thomas Herrmann has it: Sitting in a garden in Erlensee, Germany on May 27, I realized that cirrus clouds were visible all across the sky. Knowing that these clouds can provide an opportunity to observe atmospheric phenomena, I kept an eye on the sky and was rewarded by seeing the amazing circumzenithal arc, shown above. With just a little imagination, you can see seahorses floating inside the arc. Circumzenithal arcs are perhaps the most colourful of all halo-related phenomena. In fact, many people who witness them believe they're rainbows because of their beauty and arc-like shape. However, contrary to a rainbow, which forms a circle around the antisolar point, a circumzenithal arc appears, as its name implies, at the zenith. Only the portion pointing towards the Sun is visible. I still don't quite understand it.