Wish I’d had a digital camera on the time
however a cartoon should suffice,
representing two precise incomplete rainbows
that cease in midair the place they meet,
lit solely by a setting solar.
This appeared so paradoxical,
I truthfully puzzled if it was a dream.
After all, on a traditional
rainbow with two arches,
the arcs don’t contact
and the bigger one may be very a lot fainter with a reversed spectrum.
The arches schematized right here had been certainly accompanied by
typically-faint concentric bigger arcs
that additionally stopped abruptly the place they, too, met,
precisely above the primary assembly level.
Being awake, because it turned out,
I found the straightforward rationalization for this,
associated to an often-subtle
and fewer dramatic on a regular basis phenomenon
that’s readily comprehensible in nonscientific phrases.
I had sufficient info on the time
to resolve this like a puzzle, although,
and now you do too.
What was that straightforward rationalization for this odd pair of rainbows?
Notes.
Only air was between the viewpoint and these rainbows.
The much less full rainbow, to the fitting, is barely brighter
and each arches brighten the air straight under them.
The image has been revised to extra clearly symbolize
how the rainbows finish at barely totally different locations, muddled by their overlap.
 
The bigger arch ends
a bit of to left (and barely up) from the place the smaller arch ends.
 
The rainbows weren’t as thick as depicted (none are)
and had additional attribute options
that scientific pictures would reveal
to increase a vertical sample of comparable assembly factors.
 
Safe to guess that this impact was not noticed
by people greater than a century or two in the past,
though tiny animals could have skilled it
over the course of eons.
 
Some particulars of the real-life story have been altered
in an try to stymie web searches.
Here is an added diagram meant to emphasise
that the place of a rainbow relies on the route of
incoming daylight
and
that the scale and distance of any rainbow are intrinsically ambiguous
as a result of the mist that creates a rainbow is never at a single
distance and the ensuing picture occupies the identical portion of
the visible subject
no matter precise distances to particular person mist droplets.
More info could be discovered all around the web,
comparable to
Wikipedia
and (much less laboriously)
earthsky.org.
