Saturday, December 26, 2015

Christmas Full Moon 2015

Clearing skies gave me the opportunity to film the full moon this Christmas season, one that doesn’t come come around very often and the next one won’t be until 2034 . Our stretch of clear weather also brought our coldest weather of the season with the temperature at –32F/-26C Christmas morning.

On the 24th, the sky was covered with a thin overcast layer and the moon was showing a 22 degree halo for most of the morning. At other times the moon was visible through thicker clouds that didn’t have the necessary ice crystals for the formation of halos or arcs. Christmas Day broke bright and clear with visibility greater than 25 miles, just what I needed for my project I had in mind for this day. I wanted to film the setting full moon once it descended low enough to be effected by the inversion layer that creates mirages. In order to be able to do this I needed a very clear horizon to the north as that is where the moon would be setting today.

While waiting for the moon to move around to the north I filmed it with various objects around the homestead. There was nice contrast with the moon and some of the willow bushes covered with thick frost and a nice moon beam shimmering across our lake ice.

The final moment arrived around 11AM when I started my project which lasted until 12:25PM. With the temperature holding at –31F, I was glad that the wind had dropped from yesterday’s 14 mph wind and a wind chill of –54F. My camera battery had a full charge when I started, but with the cold it was blinking and about to shut the camera down when I took my last photo of the series #115.

Start of the series of photos as the moon starts showing the inversion causing mirage effect. This second photo also has a small green flash on top and what looks like a orange one on the bottom as refraction is causing colors to separate along the edges of the moon. Time 11:41 AM

Time 11:49 AM moon is being distorted more on the bottom as it gets closer to the horizon. Notice another capture of a green flash.

Time 11:54 AM another green flash can be seen and the moon has been pulled apart on the bottom.

Time 11:59 AM in this shot the two halves look almost like mirror images as the moon looks to be touching the horizon.

Time 12:03 PM Here the mirage has taken on an almost rectangle shape with a small anvil and green flash on top.

 Time 12:16 PM now just two thin strips as last of moon mirage is about to disappear. This is where my battery gave up and since there wasn’t much more to see I didn’t put in a fresh one. Also even with my fur parka and other heavy gear I was chilled and ready to snuggle up the warm wood stove for a spell.

It was fun watching the moon go from a round shape to one that was constantly shifting and becoming more flattened or elongated. To add to the thrill, I was also able to see and catch on film several green flashes. A green flash is caused by refraction causing color separation when the moon’s disk is close to the horizon.

As a side note, I was actually filming the moon below the horizon for the last 20minutes or so as atmospheric refraction causes a vertical shift of about half a degree. Since the moon’s angular diameter is also half a degree the moon is really below the horizon when the moon’s disk appears to touch the horizon.

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Arctic Smoke Signals by James W. Helmericks is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.