Lunar Corona Above Mt. Wendelstein
July 23, 2008
The above photo shows a magnificent lunar corona as observed from Mt. Wendelstein, in the Bavarian Alps of Germany, on the night of February 14, 2008. Earlier this evening, mid-level clouds had formed in a foehn wind (warm, dry orographic wind) moving over Mt. Wendelstein (1,838 m or 6,030 ft). As the Moon and clouds converged, a corona appeared which was more intense and larger than any I had seen before. Four systems of rings were clearly visible. Coronae are caused by diffraction of moonlight or sunlight by uniform cloud droplets. The intensity of this corona leads me to the conclusion that all water droplets in the particular cloud resulting in the multiple rings were of almost the exact same size. This dazzling corona covered approximately 20 degrees of sky, similar to the size of the constellation of Orion. Amazingly, it didn’t show any noticeable changes in intensity or shape for nearly 4 hours. It finally dissolved when the foehn wind broke down and the clouds began to dissipate.