6am – I step outside to walk the dog and see this amazing moon halo!
As a young girl, I remember visiting my grandparent’s house for an early Christmas. I remember getting a box of pencils with MY NAME embossed on them. Talk about special, I was the envy of my 4th grade class!
As we left for home, we stepped out into the dark night and saw a beautiful moon halo. I remember being told to count the number of stars inside the halo. The number was 25 or more. This was the number of days until a large storm would hit. Now being Michigan. . . in winter, chances are pretty good that we would have a storm. Well, on January 27, 1967, we had a whooper of a storm, just around 30 days later. Almost 3′ of snow was deposited overnight! We were stuck at home for days.
This morning, as I saw this moon halo, I thought of that memory, years ago. I quickly counted the stars within the halo this morning, I saw only one or two. Hmmm. . . wonder if middle Tennessee is going to get a storm?
Folklore aside, the moon halo was caused by the refraction of moonlight, from ice crystals in the upper atmosphere. The shape of the ice crystals result in a focusing of the light into a ring. Since the ice crystal typically have the same shape, namely a hexagonal shape (LOVE THAT SHAPE!), the moon halo is almost always the same size.
Folklore has it that a ring around the moon signifies bad weather is coming, and in many cases, this may be true. It was in the case of my childhood memory.
So how can a halo around the moon be a predictor of weather to come? The ice crystals that cover the halo signify high altitude, thin cirrus clouds that normally precede a warm front by one or two days. Typically, a warm front will be associated with a low pressure system. . . which is commonly referred to as a storm.