Was at Fantasy Canyon last week and saw this odd halo around the sun that stuck around for a decent while. To the naked eye, it looked rainbow colored. I asked some folks I know and they said variously that it was a sun halo, a sun dog, and a 22 degree halo. I've never seen this happen before. Can someone confirm what this is?
Whatever it is, I feel very lucky to not just have witnessed it, but to have witnessed it in a place with terrain I could use as a vertical foreground. This was around noon, so I was shooting nearly straight up.
It's hard to tell the angular scale, though it seems like it could well be a 22° halo. A sun dog is something different, that is a brightening in a halo to the left and right of the sun. What focal length was this taken at? FF or APS-C sensor?
kirbic wrote:
It's hard to tell the angular scale, though it seems like it could well be a 22° halo. A sun dog is something different, that is a brightening in a halo to the left and right of the sun. What focal length was this taken at? FF or APS-C sensor?
M4/3 from an Olympus EM1 Mk2, 7mm for the horizontal shots, 9mm for the vertical one, f/8 for the first two, f/20 for the last one (on account of trying to get the sun star.)
Ah, so for the horizontal shot, we are looking at a 14mm equivalent in FF terms. That helps. Gives us a FOV of about 115°. The halo is a bit under 1/3 of that so it's close to what you'd expect for a halo with 22° radius. Because circles are "stretched" near the edges of a wide-angle rectilinear frame, we do expect the roughly-centered 22° circle to be a little larger than you'd calculate by dividing 44 into 115.
I would conclude, yes, 22° halo.
Meteorologically, it's a halo. In a rarer event, it can literally ring the sun, immediately around the sun's sphere - that's called a corona. Take it from an old weather forecaster.
kirbic wrote:
Ah, so for the horizontal shot, we are looking at a 14mm equivalent in FF terms. That helps. Gives us a FOV of about 115°. The halo is a bit under 1/3 of that so it's close to what you'd expect for a halo with 22° radius. Because circles are "stretched" near the edges of a wide-angle rectilinear frame, we do expect the roughly-centered 22° circle to be a little larger than you'd calculate by dividing 44 into 115.
I would conclude, yes, 22° halo.
Neat, thank you for confirming! I wouldn't have thought to do the math like that.
Taperwing wrote:
Beautiful. Even approaching retirement, it is still possible to learn something new everyday.
