a circumhorizontal arc:
is not the same thing as a circumzenithal arc:
Earlier in the summer, I posted the first image from Carly Todd at Camp Celo. I mistakenly called it a circumzenithal arc. It is actually something more rare: a circumhorizontal arc. How can we tell? Take a look at the order of the colors in the first image. The red is on the inside of the arc, which is the opposite of a regular rainbow (red on the outside of the arc). Compare Carly's with the image Kirby sent me (second one above). The circumzenithal arc has the red on the outside like an upside down rainbow. (Did you remember that red is on the outside of a rainbow? I've been seeing rainbows all my life, and I had to double check because this whole thing got me really turned around.) Below are two diagrams showing the formation of these and the reason for the difference in color order (
from this excellent site). Why does this matter? Because it makes me look at rainbows more closely. But why is looking at rainbows closely valuable? It helps me feel just a little more love for everyone and everything. That includes you, weather nerd or friend who is still reading this. And while I'm at it, a big thanks to Carly and Kirby.
Circumhorizontal Arc formation (higher angle):
Circumzenithal arc formation (lower angle sun):
Jeff,
ReplyDeleteThat's totally cool with a fascinating explanation. Thanks for posting it.
Janet Ghigo