Scrutable

Nice, thanks

I have seen complete double rainbows a few times, all in Colorado. But that's a different phenomenon. Still cool tho. But this is wild stuff.

Cue conspiracy theories on social media...

Atmospheric Optics is an excellent site with a complete catalogue of known phenomena and how they occur.

These are all examples of halos. Apparently the 22 degree arc - circle around the sun - sun dogs, and the tangent arc at the top are all quite common, more common than rainbows, but probably frequently overlooked, or not often appearing in as clear and bright fashion as these pictures. Considering how often I see rainbows from out of the window behind me, I must be missing them often.

The picture at the bottom on the BBC article, from near Penrith, shows some rarer halos. My reading of this diagram of rarer halos suggests it includes a supralateral arc.

IvanV wrote: ↑

Tue May 30, 2023 9:46 am

These are all examples of halos. Apparently the 22 degree arc - circle around the sun - sun dogs, and the tangent arc at the top are all quite common, more common than rainbows, but probably frequently overlooked, or not often appearing in as clear and bright fashion as these pictures. Considering how often I see rainbows from out of the window behind me, I must be missing them often.

I'd say that sun dogs are roughly as frequent as rainbows in England, but the others are considerably rarer -- I've only seen a 22 degree halo a couple of times. I can think of several reasons why they may be observed proportionately less often:
- That strange psychological thing where, given a rather but not very uncommon object, you can never see it for the first several decades of your life, but then after the first observation, you get your eye in and see it regularly.
- Rainbows are well-known, so if you see one, you know what it is; whereas other atmospheric phenomena are dismissed as a sort of rainbow (e.g. the BBC's "upside down rainbow", for something very different) or just a weird glitch in the sky.
- Rainbows normally extend to ground level, whereas most other atmospheric phenomena tend to be at altitude, and we don't tend to look up that much.
- Rainbows are often very large. Sundogs tend to be quite small.
- 22 degree halos are in the direction of the sun, a direction in which people are particularly averse to looking.

A number of years ago, I posted a photo I had taken of sundogs over at the other place. It was the only time I had ever seen the phenomenon that I can remember.