What: A couple of weeks ago I managed to spend a bit of time outside at night. Between brief breaks in the clouds, the moonshadows were incredible. I was amazed at how easy the tracking was. It seems like the voles and other subnivean species (those that live beneath the snow) have fared pretty well with the ice crust, which buffers them from both the frigid air temperatures we’ve had as well as from all those predators that would delight in eating a vole. I followed a fox for awhile and it never broke through the ice. I wonder if they shift their diet this time of year to go after things that live above the snow, like rabbits, squirrels, and even fruit.
Moon’s waning now. I wanted to post this in relation to yesterday’s posting on sun halos. The phenomenon in the above photos are a similar yet somewhat different process. The corona in the picture forms as a result of water, not ice crystals, diffracting light from either the sun or the moon. The angle of diffraction is much reduced and therefore forms a much smaller ring around the sun or moon. They are far more common to observe around the moon than sun. Sun coronae appear much closer to the sun itself and, unlike with the more distant rings of sun halos, are therefore obscured by the sheer intensity of the sun’s light.
Coronae are associated with thin altocumulus (as I observed) as well as altostratus clouds. The thin cloud covered made for these beautiful breaks in the clouds where light would pour across the snow illuminating the woods. Unfortunately by the time I was heading out and spotted the gray fox tracks, the clouds had thickened and I could no longer see the shadows from the sun.
