The Moon Halo

Upon stepping outside this evening, I was greeted by an unexpected sight: a gibbous moon surrounded by a large ring of light. This phenomenon is referred to as a ‘moon halo’. The appearance of a moon halo is purely an optical effect. Moon halos may appear on nights when there are very high thin clouds (cirrus clouds) around 20,000 feet. These clouds are filled with tiny ice crystals. The ice crystals act like prisms refracting and reflecting the light, thereby creating the appearance of a halo around the moon.

There is a folkloric belief that a moon halo is a sign of an impending storm. This actually turns out to be mostly true. While cirrus clouds do not bring rain or snow themselves, they are often the forerunners of the low pressure systems that do bring precipitation. Another belief is that the number of stars within the halo indicates the number of days until the bad weather arrives, though this one doesn’t seem to hold much water, as you might imagine.

The moon halo was an unanticipated and beautiful sight. It is easy to get so involved in our days and busy lives that we miss these little gifts that are all about us if we just take the time to look around (or above in this case). Looking up at the shining halo around the moon tonight, I felt very fortunate to be there to see it and to have the time to stand out in the cold evening with my little son just gazing upward.

I took some bad pictures on my phone that I won’t make you suffer by posting. Fortunately, there are a number of better photos of moon rings available from Wikimedia Commons:

By Radoslaw Ziomber (Own work) [CC-BY-SA-3.0], via Wikimedia Commons
By Radoslaw Ziomber (Own work) [CC-BY-SA-3.0], via Wikimedia Commons
If you’d like to see some very impressive photos of both lunar and solar halos, visit:

http://earthsky.org/space/what-makes-a-halo-around-the-moon

When have you witnessed unexpected moments of beauty in nature?

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