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Ring Around the Moon

February 4, 2010

As the full moon crossed the zenith of the night sky above the ‘glades and the tide rose in the salt marsh I trudged out into the deepening water to frame this shot with some dead trees (of course). High cirrus clouds moving on the currents of the upper atmosphere created this gorgeous halo around the moon.

3 Comments leave one →
  1. February 4, 2010 9:34 pm

    I heard a lot of people talking about the rings around the moon. I wonder what caused that phenomenon?

    I love this shot, Jim. Of all your subject matter, I really like your cloudscapes and moonscapes best. Awesome shot!

    • February 4, 2010 10:04 pm

      In answer to your question, I know a bit about what forms the halo. This is an example of the most common form of atmospheric halo, called the 22 degree halo. Light passing through hexagonal ice crystals in the cirrus clouds is deflected through 2 facets of the crystal and the minimum total angle of deflection is approximately 22 degrees and forms the inner red ring of the halo. Imperfections in the shape of many of the crystals within the cloud cause wider angles of deflection as well spreading the other colors of light all the way out to 50 degrees. The result is a hole with no optical phenomena occurring from the moon out to 22 degrees, a sharp start of the halo with a red ring at 22 degrees, and a gradual spread and fade of the other colors of the spectrum out to 50 degrees. It is very large in the sky and I needed to use my 10-17mm fisheye lens to be able to fit it into a reasonable composition.

  2. February 5, 2010 9:49 pm

    Wow! Thanks for that explanation, Jim. It’s really cool looking and this shot is excellent.

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