... Not all rainbows are as colorful as their
reputation suggests.
There are some spectacular monochrome
rainbows when the conditions are right.
The cooler shades drop out of the rainbow
leaving bands of yellow, orange, and red.
Sometimes the rainbow narrows down to a
bright red streak of light.
The rainbow goes monochrome simply
because there are no other shades of
light to be had.
Sunsets cast a red glow on the world because
the gas in the atmosphere scatters blue light
filtering it out.
This isn't noticeably during the day, except
as a slight lemony yellow cast to sunlight
but when the sun is at the far end of the
world with a lot of atmosphere between it
and the viewer the blue gets scattered away.
For any rainbow to appear, there needs to be
some water, and monochrome rainbows are likely
to happen just after rainstorms or during times
of heavy mist.
The water droplets further scatter certain
wavelengths of light intensifying the effect.
As there is no violet, blue, green, or sometimes
even yellow light for the water droplets to refract
the rainbow consists of an arc of red.
Some people also see white monochromatic
rainbows.
When particularly thick fog or clouds scatters light
less precisely than falling rain, light can still form an
arc in the sky.
The colors get mixed together, and the arc shows
up as a large streak of white.
It's basically a lit-up cloud.
Has anybody here ever seen a
monochromatic rainbow?
Original post by Esther Inglis-Arkell