Wish I’d had a camera at the time
but a cartoon will have to suffice,
representing two actual incomplete rainbows
that stop in midair where they cross,
lit only by a setting sun.

<img src="https://i.sstatic.net/Vkk8U.png">

This seemed so paradoxical,
I honestly wondered if it was a dream.
After all, on a normal
[rainbow with two arches](https://en.wikipedia.org/wiki/File:Full_featured_double_rainbow_at_Savonlinna_1000px.jpg),
the arcs do not touch
and the larger one is very much fainter with a reversed spectrum.
The arches schematized here were indeed accompanied by
typically-faint concentric larger arcs
that also stopped abruptly where they crossed,
exactly above the main crossing point.

Being awake, as it turned out,
I discovered the simple explanation for this,
related to an often-subtle
and less dramatic everyday phenomenon
that is readily understandable in nonscientific terms.
I had enough information at the time
to solve this like a puzzle, though,
and now you do too.

<sup><sup></sup></sup> &emsp;&emsp;&emsp;&emsp;&emsp;
**What was that simple explanation for this odd pair of rainbows?**

<sup><sup></sup></sup>
**Notes.**
The smaller arch is _slightly_ brighter.
Only air was between the point of view and these rainbows.
The rainbows were not as thick as depicted
and had further characteristic features
that scientific photography would reveal
to extend a vertical pattern of similar crossing points.
Safe to guess that this effect was not observed
by humans more than a century or two ago,
although tiny animals may have experienced it
over the course of eons and written poetry about it.
Some details of the real-life story have been altered
in an attempt to stymie internet searches.