A ridge of high pressure will continue to build over the Great Basin, raising temperatures into the upper 80s and low 90s by the end of the week. Skies will remain mostly sunny through the end of the week, with a few clouds coming back into the region early next week, as the ridge weakens and temperatures fall back into the lower 80s.

As many of you know, viewers send me all kinds of pictures from the region when interesting weather occurs. Rainbows are a favorite, and I got several in my in-box last week from where thunderstorms were occurring. But what causes the continuous arc of color in a rainbow? The optics of a rainbow is very simple on the one hand, but get very complicated when it comes to putting it all together.

Double Rainbow Wide Desktop Background

First the simple part: Sunlight, made up of the entire spectrum of visible light, can be broken down into its component colors by passing it through a prism. A raindrop can act as that prism. As the light enters the drop, the light is bent (refracted) and split into all the colors. These then reflect off the back of the drop, and when they pass through the front of the drop again, they are bent (refracted) still more. (I’ll have more tomorrow)