When I arrived at the gym about 8:30 this morning the sun was up and midway between the sun and a huge ascending bank of clouds was a bright spot displaying all the colors of the spectrum. Of course I grabbed my camera and jumped out of the car to photograph it. I’ve featured this phenomenon in my blog in a past post called Rainbow Clouds a couple of years ago but I took that shot was near sunset up in Redding.
This is sometimes called Fire Rainbow because when it appears in cirrus clouds, those wispy horsetail like clouds, the colors look like flames. This happens when the light reflects off ice crystals in the atmosphere in an optical phenomenon called circumhorizontal arc—I love Google! This shot shows only a tiny bit of the arc which was never entirely visible this morning.
In an effort to get true rainbow colors in the photograph, I had to make some significant exposure adjustments. I took this at ISO 100, f/16 and 1/1250 second shutter speed. Even at that, I should have further increased the shutter speed or the f-stop because when I downloaded the shots, the rainbow colors were dim and the sky and clouds were dark and dull. For this photo, I added a little clarity, vibrance, and tonal curve in Lightroom and then decreased the luminance for all the colors.