I’m taking a walk with my dog Lola this afternoon, enjoying the sunshine and not waking up at 1:30 AM. On our way back from checking the mail (junk mail and a bill) I saw something pretty cool in the sky:
Similar to rainbows, haloes are faintly colored arcs that sometimes appear around the moon and the sun. They’re caused by light refracting (bending) through the ice crystals inside cirrus clouds (the high, wispy clouds outside today).
Below is the visible satellite image from 12:45 PM, which shows plenty of cirrus clouds over Middle Tennessee. At noon the Nashville International Airport reported a layer of cirrus clouds at 20,000 feet overhead.
I thought about but couldn’t recall ever seeing two haloes at the same time, so I checked one of my favorite weather books and indulged in a moment of geekiness on my day off.
What I learned:
The outer halo is called a 46 degree halo, and is rarer than the inner halo (called a 22 degree halo). Both are produced by sunlight bouncing through the inside of randomly oriented ice crystals in the upper atmosphere. Each halo is red on the inner edge and blue on the outer edge.
Here’s another picture of
the double haloes.
Enjoy the weather!
P.S.
Timothy Hollmann sent us this picture, as well
