Woof?

One of our esteemed viewers left a message on our answering machine this morning, asking what the rainbow-colored thing next to the sun was yesterday evening. I immediately knew what she was talking about, since I had also seen it. It's what's known as a parhelion, mock sun, or (the name that's most common), a sundog.

When we see them, it's almost always because of ice crystals being present quite a ways up. Those ice crystals, if shaped and positioned just so, will refract (bend) the sun's light. We then see the visible spectrum of light (the colors of the rainbow) up in the sky in the form of a blob.

Sun dogs work similarly to rainbows in that the light is being bent in such a way that we think the light is coming from a place that it's not. That's what the dashed line on the image above illustrates - our eyes and brain think that the light is going a straight line, so we see the sundog in a place where there actually is nothing!

Ice crystals tend to show up in the sky ahead of weather systems... usually warm fronts but not always. So when you see sundogs or halos or other similar phenomena, you know that change may be on the way! We do have a cold front slipping through, but it's rather weak. Pleasant weather will continue - just a touch cooler tomorrow thanks to an easterly wind.