Q&A-Nature & Science

Topics

Are there colors that exist only in nature?
Where does the color of a blue jay feather come from?
What is the green flash?
What optical properties make the sky blue?
Color - Frequency / Wavelength - Verification

A Color Existing Only in Nature

Question:
I was wondering if there are any colors that have never been reproduced artificially (only exist in nature)? What I meant was: is there a color that we can see in nature that has never been reproduced artificially? The reason I am asking is that someone once told me that he had heard of a color that existed in the natural world but has never reproduced. Swoozy

Chris Willard
Swoozy, your question has a faulty premise, namely that it implies there is color in nature. There is no color in nature, for that matter, nothing has color. All things are are molecules that absorb, transmit or reflect certain portions of the electromagnetic "spectrum" (not to be confused with the spectrum that means rainbow). The only reason we perceive energy as color is because we have little computers (eyes) that can process that small range of energy within what we call the spectrum. Thus since all colors can only be according to our eyes, your question basically says: Can I see any colors I can't see. On the other hand if we limit the question to can we find colors in the real world that we perceive (noting we must SEE the difference and not alllow a difference in reality, for example the sun is an obvious example, yet filming the sun in movies gives us the same sensation of glare) as different or unduplicatable from any technologically produced color the answer would be trickier. Do pigments = artificial? Then does florescent paint = artificial? Are conceptions of color nature, and thus not reproducible since no red can match the super saturated red I think of ? Perhaps you can think about this and attempt to clarify your question.

Mac
Swoozy, I suppose this is pushing it a bit, but... One might be hard pressed to 'reproduce artificially' or make 'at all', a total black and total white (if we choose to include them as colors)...and why wouldn't we? Then again, nature might be hard pressed to do it too. How would we make a pure black? Maybe we'd need to define it first? Maybe Black would be a color that gave off absolutely no light? It absorbed everything? every visible energy? oh heck, how about all energies? I suppose we'll need to put the Black color swatch (or whatever we're going to use) into a vat of liquid hydrogen too. Take it down to zero degrees K (Kelvin). That's going to be tough though. We'd need to get it to absolute zero to ensure there was no even as much as a wiggle out of those atoms. Sort of like being in deep space? [But even then, I think there is some stray energy whipping around]. Hmm. And what about that White? A thing that 'reflects' all visible light? Wait. Isn't that a pocket mirror? I wanted Pure White. Titanium White? No....whiter. Much Whiter. This is difficult. Maybe mother-nature isn't going to be able to do this either. Maybe the world just isn't Black & White, but is more shades of Grey. Food for thought. Mac

LKPete
It would be supreme arrogance to assume that we (people, that is) have already "artificially" reproduced every color we've seen. We have probably come darn close, though. I've also seen info about deep water fish that are colors not seen on the surface, or even closer to the surface. Some of these fish can change their colors by what they eat. Other posters make excellent points about perception not being entirely (or exactly) universal, and raising the question that if mankind creates a color why does that make it "artificial"? After only a few short steps into this topic you find you've slipped into very deep philosophical and other waters. Good fishing.

Saraimana
On a marine-life documentary I once saw, I came across the strangest color I have ever seen on a fish. It could have been the deepness of the ocean that made the fish's scales look so strange, but I doubt it. i doubt it because of the way I can discribe the color. It was not gray, but it was mirror colored. You can only imagine what this is like, but I have never seen this color before this documentary and I have not seen the color sense.

Robin
I'm not an expert, but I think I understand the point of the question. I often see in flowers colors that are more vivid that the brightest silks. For example, the blue of a lobelia flower is more intense than any blue dye or pigment I've seen. I have never seen the blue of a lobelia flower anywhere but on a lobelia flower. Structural color is an even better example - a peacock feather has 3 shades of blue that no pigment can reproduce, because the color comes from the microscopic structure of the feather. That's not to say that science couldn't reproduce it someday, but they haven't yet. Beyond that, there are probably colors that we are capable of percieving that exist nowhere in the world, neither natural nor man-made. For example, very saturated blues and turquioses are hard to find in matter, so we never see them.

Phare-Camp
I once saw a meteor explode when it met the atmosphere. The shade of blue produced by the explosion was one I have never seen before or since.

Where does the color of a blue joy feather come from?

I am trying to find another reference to statement I found about a blue jay feather are not a blue pigment, but the color is caused by structural color. I also wanted comformation on the blue found in a human's iris. The statement is there are no blue pigment in a blued person iris. The blue is the result of structural color. Please explain.

Willard:All color is caused by certain molecular structures reflecting certain wavelengths of electromagnetic energy. Nothing in the world is colored. Your questions seem a bit different: the iris is bluer when it has less iridium in it. A bird's feather like a peacocks often is seen to be colorful because of interference colors, colors arising from parallel ridges in the structure that bounce light back in certain ways to us. Hazel Rossotti's book Colour: Why the World Isn't Grey gives a great overview of your question 'structure-------->color' in regard to nature.

What is the green flash seen at sunset along the beach?

brent roden
Have you seen it and along what beach? What time of the year? There are a few speculated causes. They revolve around the spectrum of the rainbow and that you move, relative to the sun's light, in a position of seeing the light prismically seperated to green. Red, green a blue are the primary colors of light. When you see the green flash, it is the reflection of that green band of light wave length off the atmosphere.
A.T.Young

Randy Crawford
Stare at something red for a while and when you avert your stare, you see aqua. The same applies for the sun Stae at sometnhing as intensely orange as the sun is before it dips below the horizon and you get a green blip as it disappears.

What optical properties make the sky blue?

Question:
What optical properties make the sky blue?

Bertrand Fabre
G'day! It's got something to do with bending of light. Remember the album by Pink Floyd with that glass prism? Well white light entered the prism and a full colour spectrum came out. Blue doesn't need much bending. The oranges and red need more bending from white light. When the sun sets, the sky goes orange, red and even purple. Interesting thoughts anyway. Goodluck

Color - Frequency / Wavelength - Verification

Question:
Please verify the frequency and wavelength of colors.

cwillard
This seems pretty obvious...good sources are the Hurvich book, Ratliff, or the Williamson/Cummins books. Hurvich lists the wavelengths associated with colors as (in nm's) 475 blue 500 green 580 yellow 700 red but we must remember these are narrow band regions which I assume you must be speaking of here to rule out metamerism. violet would be from 400-450 nm according to the w/c book. But I'm guessing you know all this....I wonder what you are digging at here. I'm not sure I have the conversions handy, although I might be able to dig them out. I can give you the formula for the vacuum if you need it. : } but again I'm guessing you are sort of beating around the bush toward a more specific question, and I'm very curious as to what that is!!!

Mac
Chris, Thanks. Me beat around the bush?! Depends on the color of bush. :-) So you say (that 'they' say): 475nm=blue 500= green 580= yellow 700= red nanny meet hers? I grabbed another book and it said: 450nm=blue 530 =green 600 =yellow er, or 589.3nm? or or or 725 =red And another book and another book.... As many books as there are colors in the rainbow? My physiology books say one thing, engineering texts another, color calibration another; I suppose NIST has yet another. Maybe people are measuring color wavelengths on a rocket ship to Andromeda and suffer from Doppler shift? :-)

cwillard
Reminds me I recently saw the movie "Andromeda Strain" for the first time again in years. It was interesting. But to the point...you are a pro at this so I will use your technique of questioning... If I showed you 1,000 reds and asked you to pick the reddest one, would that match the red someone else picked? Probably not. Thus, I think this accounts for the differing attributions of narrow band wavelengths to color. My educated hypothesis is these purest primaries (if we may call them that since we know the spectrum is arbitrarily broken into discreet color segments -- just as with Newton who revised his originally perceived 11 colors of the rainbow down to 7) are the result of a best fit with the technology they are used for. Thus the reddest red in television will provide the largest gamut of mixed colors where in paint you may have a different one. But to pursue this on a more physiological level, studies have shone afterimage colors differ slightly when subjects are asked to match them against standards....some are a bit more saturated, some less so, some skewing the color slightly...and I would infer from this that the exact color percieved probably also differs in the same slight manner. This of course might find a narrower range when the primaries red, green. blue are judged only by maximum retinal response but how do we consider more complex mixes.