sundog.htmIf you are a fan of pleasant sunny weather have we got a week for you! Gothamist doesn't have much to write about in terms of the forecast. Sunny and mild, highs in the mid-70s (which is ever so slightly above normal), lows in the mid-50s (ever so slightly below normal) everyday through Thursday. There may be a few clouds this afternoon. A slow moving cold front may get here by Thursday night, bringing with it a bit of rain on Friday and a cooler weekend.

Gothamist was going to work on Friday morning when we saw the rainbow-like object in the photo above. That optical phenomenon is commonly called a sun dog or mock sun, but is technically known as a parhelion, which is greek for sun dog or mock sun. Cirrus clouds, like those in the picture, are composed of ice crystals.

All ice crystals are six-sided, but they can be elongated like a pencil or flat like a plate. The ice crystals that make sun dogs are not only flat plates, but they are also oriented horizontally as they fall through the cloud. With that shape and orientation the ice crystals bend the sunlight at an angle of 22 degrees, resulting in bright spots on either side of the sun. If you hold your fist up at arm's length and cover the sun with your thumb, so you don't fry your eyes, the sun dog will be just off to the other side of your hand, with a reddish color pointing toward the sun. Had the ice crystals been jumbled up instead of horizontal the result would have been a halo around the sun.