Is pink rainbow real?

No, pink rainbows do not naturally occur in nature. Rainbows are optical illusions created by the refraction, reflection and dispersion of sunlight through water droplets. The colors we typically see in a rainbow are red, orange, yellow, green, blue, indigo and violet – the colors of the visible light spectrum. We don’t see the color pink because there are no pink wavelengths of light.

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Why are rainbows the colors they are?

Rainbows appear the colors they are because of the way light interacts with water droplets. When sunlight enters a raindrop, some light is reflected off the inside surface of the drop. The rest of the light is refracted (bent) as it travels through the curved surface of the drop. This refracted light is dispersed into the colors of the visible light spectrum, with each color bending at a slightly different angle, creating the rainbow arc we see.

The color order we see in a rainbow is determined by the wavelength of visible light. Light ranges from short wavelength violet/blue through to long wavelength red. When white light is dispersed by water droplets, the colors separate based on wavelength, with red bending the least and violet bending the most. This separates sunlight into the sequence red, orange, yellow, green, blue, indigo, violet – the colors of the rainbow.

Why don’t we see the color pink in rainbows?

We don’t see the color pink in rainbows because there is no pink wavelength of light. The visible light spectrum ranges from violet/blue light with short wavelengths, through green and yellow light, to red light with long wavelengths. There is no pink light wavelength within this spectrum.

The color pink is created when some wavelengths of red light mix with shorter wavelengths of purple/blue light. But in a rainbow, the different wavelengths remain separated rather than mixing together. So we don’t see a pink band form in a rainbow.

Could artificial pink rainbows be created?

It may be possible to artificially create the appearance of a pink rainbow by using colored lights or filters. While not true rainbows made from refracted sunlight, these illusions could mimic the effect:

Colored stage lighting could combine deep red and pale purple lights to give the impression of a pink rainbow.
A glass prism or water droplets could disperse regular white light through a pink filter or stained glass, separating the light into a rainbow pattern.

Light projecting devices with red and blue LEDs could overlap the colors to form a simulated pink rainbow arc.

However, these would not be true natural rainbows. They would rely on added colors rather than the dispersion of pure sunlight into its natural spectrum. The pink effect would be an artificial optical illusion.

Could rainbows appear pink at sunrise or sunset?

Rainbows may take on more pinkish hues during sunrise or sunset when the quality of sunlight is redder. As the sun dips below the horizon, sunlight has to travel through more atmosphere which scatters away the shorter blue and violet wavelengths. This leaves the longer red, orange and yellow wavelengths to shine through, creating more reddish and pinkish sunsets.

In theory, this redder sunset light could then create rainbows with stronger red bands, perhaps mixing slightly with the blue/violet bands to give a subtle pink tint. However, the effect would be very slight, and natural rainbows would still lack a definite pink band.

Could rainbows look pink against pink skies or backgrounds?

Rainbows may appear to have a pink hue when seen against strongly colored pink skies and backgrounds. While the rainbow itself remains its natural color spectrum, the contrast with the pink sky can give the illusion of the rainbow taking on those background colors.

For example, rainbows viewed at sunrise/sunset may seem to blend with the pink hues of the sky. Or double rainbows against a pink building may mimic those colors in their weaker outer bands. But the rainbow colors themselves remain the same.

Are there any natural pink rainbow phenomena?

There are some very rare natural optical phenomena that can create a pink arc or rainbow effect in the sky:

Pink sprites – Brief flashing columns of pink or red light above thunderstorms, caused by electrical discharges.
Noctilucent clouds – Electric blue or pale pink clouds forming at high altitude in the atmosphere.

Cloud iridescence – Pink and blue colors diffracting through thin clouds edged by sunlight.

However, these are not true rainbows created by the refraction and dispersion of sunlight through raindrops. They have other causes, usually electrical or atmospheric effects.

Could genetic mutation cause pink rainbows?

It is theoretically possible but extremely unlikely that a genetic mutation could cause someone to see rainbows as pink instead of their normal color spectrum. This would require:

A mutation causing a major change in the cone cells of the eye that detect color.
This altering the normal light absorption and wavelength detection of cone cells.
Specifically shifting blue/violet receptor cones towards the red end of the spectrum.

While leaving other cone cells and color perception unaffected.

Such a specific genetic change may allow someone to perceive rainbow light in a limited pink hue. But it has likely never occurred naturally. Genes and vision are complex and precisely calibrated by evolution, making such a specific mutation fantastically improbable.

Conclusion

In summary, true natural pink rainbows do not occur in nature. Rainbow colors are determined by the wavelengths of sunlight, with no pink light to form a pink band. However, pink rainbow illusions may be artificially created with lighting effects. Rare atmospheric phenomena can also mimic rainbow-like optical effects in pink. But pink rainbows do not naturally appear in the sky when sunlight interacts with rain.

Rainbow Color	Wavelength
Red	620-750 nm
Orange	590-620 nm
Yellow	570-590 nm
Green	495-570 nm
Blue	450-495 nm
Indigo	445-450 nm
Violet	380-445 nm

This table shows the wavelengths of light corresponding to each rainbow color. There is no wavelength that would produce a pink color in a rainbow.

Is it possible to see a rainbow anywhere other than the sky?

Yes, rainbow effects can be seen in various other places besides the sky:

Water spray – Rainbows in spraying water from fountains, waterfalls, waves crashing, etc.

Water surfaces – Bright rainbow patterns formed on still pools of water.
Water droplets – Mini rainbows in droplets and bubbles, like those formed by a running hose.
Mirrors – Rainbows reflected and dispersed in mirrors and prisms.

Crystal objects – Rainbows refracted through clear crystals, chandeliers, glass objects etc.
CDs – Spectral bands diffracting off the closely spaced grooves of CDs.
Oil slicks – Thin layer of oil on water disperses light into rainbow swirls.

Soap bubbles – Interference of reflected light off soap bubble surfaces.
Eyelashes – Diffraction of light through eyelashes spread over the eyeball surface.

Any situation where white light is reflected, refracted and dispersed can produce rainbow-like optical effects and color banding. But sky rainbows formed by sunlight and raindrops remain the most vivid and pronounced.

What causes double rainbows?

Double rainbows are formed when sunlight is reflected twice inside raindrops:

Sunlight enters the drop and is reflected off the back, dispersing into a spectrum of colors.
Some of this colored light is reflected again off the drop’s surface, creating a second rainbow.

The secondary reflection inverts the order of the colors in the second rainbow.

The secondary rainbow is fainter and broader than the primary rainbow because the light is reflected twice, losing more intensity. The double reflection also shifts the secondary bow to the outer edge of the rainbow spectrum.

Can rainbows form circles or arcs greater than 180 degrees?

In theory, rainbows could form full circles or arcs spanning more than 180 degrees around the sky. But in practice, typical rainbows remain less than 180 degrees due to the specific angle required between the sun, raindrops and viewer:

Rainbows form at an angle of 42 degrees from the direction opposite the sun.
To see a full circular rainbow, the viewer’s head would have to block sunlight at this 42 degree angle.
Since people’s heads aren’t wide enough, we can only ever see up to 180 degrees of rainbow.

However, rainbows can form more than half-circles when viewed from high altitudes. From an airplane for example, more of the rainbow arc comes into sight as the viewer’s perspective changes.

Are rainbows seasonal or can they be seen year-round?

Rainbows can occur at any time of year as long as the necessary conditions are met. To see a rainbow, you need:

Sunlight shining from behind the viewer onto falling rain.

Raindrops that are spherical rather than oblong shaped.
Suspended droplets that air can refract light through.

These conditions can occur at any time of year, but rainbows tend to be more common in warmer seasons when rain showers are more frequent. However, rainbows can still form in cold weather when sunlight refracts through icy precipitation and frozen rain droplets.

So while rainbows may be more frequent or last longer in spring and summer, they can potentially be observed in any season as long as the optics of raindrops and sunlight allow.

What makes rainbows disappear?

Rainbows are delicate optical effects that will disappear when viewing conditions change. Some factors that can make rainbows vanish:

Moving out of the narrow band where rainbow illumination occurs.

Light intensity or angle of sun changing as clouds pass.
Rainbow-forming raindrops falling and new ones not taking their place.
Rain shower ending or moving to block sunlight angle.

Viewing angle shifting so sunlight no longer refracts at 42 degrees.

Essentially, rainbows disappear when the specific alignment of raindrops, sunlight and viewer’s line of sight gets disrupted and light no longer refracts and disperses into spectral colors.

How are rainbow colors produced?

Rainbow colors are produced by the refraction and dispersion of sunlight through water droplets:

As sunlight enters a drop, it slows and bends (refracts) while passing through.
Different wavelengths (colors) refract by different angles based on their energy.
Longer red wavelengths bend the least, shorter violet bend the most.

This separation of colored light is called dispersion.
Light reflects off the back of the drop, then disperses out towards the viewer.
The dispersion creates the sequence of rainbow colors.

Without dispersion separating the colors, rainbows would appear white. The splitting of sunlight into distinct bands of color creates the colorful spectrum of the rainbow.

How do rainbows form upside-down in water spray?

Rainbows can form upside-down or arched in spraying water when sunlight is refracted through ascending water droplets:

In sky rainbows, sunlight disperses through descending droplets.

In spray rainbows, droplets rise up towards the sun.
Light enters the bottoms of the droplets and leaves through the tops.
This inverts the rainbow, arching it upwards.

The inverted rainbow orientation is caused by the flipped direction of sunlight entering raindrops that are shooting up rather than falling down. The same principles of refraction and dispersion apply, just reversed.