A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2017 May 17, 05:04 -0700
Few days ago the clouds (like these, the cirrus uncinus and cirrus fibratus) were obscuring the Sun in the evening. One part of the cloud layer was colored like a raindow sector. The red band was at ~20°10' from the Sun, the violet band was at ~20°30'. I.e., unlike the usual (seen away from the Sun) raindow which has violet band closer to the center of its' arc - this one was "reversed". It was around the Sun and color order was reversed too.
I could not find the data about the angular width of the usual rainbow, but I vaguely recall it is wider than those 20° radius I measured for that halo. Next time I see a regular rainbow - I hope I'll have the sextant with me.