12/30/2004: Green flash at sunset

[linknoid]

Originally Posted by capnhowdy

as an artist , I'm compelled to post:
you cannot acheive, (w/ paint & canvas) what I'm reading here. One cannot confuse the spectrum of color with what is created with physical color mixture. The color spectrum is a basic guideline to the physics of color, which is scientifically the explanation to "everything that shallow people will relate to". There are no limits to color and the effects on the mind. Which is to say.... what you may see is not what someone else will see. I've tried some mixtures as suggested in this thread, and if You'll do the same you'll realize that it is totally hypothetic and "textbookish". Color, let alone art, is what is absorbed in one's mind & their imagination. What looks green to me may be teal to you. What is provocative to you may be calming or docile to me. In the minds eye, of course. There is no scietific proof that we even see color at the same level or hue or tone, etc. Especially intensity. Color is a very personal thing. " I saw red" may mean to you that you were really pissed while to someone else may mean they were totally elated.

As a physicist (well not really, but I did major in it in college for a while), I would say that you're correct (at least in this comment, the next one where you say to throw out the spectrum completely is going overboard). In my explanation I specifically avoided going into the complexities of perception or even the details of what happens when you mix color. The point was to explain the basics of how colors work to someone who claimed not to know hardly anything about it.

Each person's eyes respond to slightly different wavelengths. In fact, some men only see 2 shades (they're colorblind), and some women actually, because of genetic issues, have 4 types of cones instead of 3, and they actually see a much different colors (and they're genetics mean if they pass on the genes that produce 4 colors for them, their sons will be colorblind).

But once you get past the issue of how each person responds to the various (and infinite) combinations of the colors of the spectrum, then you have to deal with where that combination of wavelengths and intensities are coming from.

First you have the light source. Each different source is different. The sun produces a relatively complete visible spectrum, resulting in very white light, but by the time it's passed through the atmosphere, a lot of the blue end has been scattered out, and even then the spectrum changes based on the time of day, the weather conditions, the pollution in the air, etc. And there are many other different light sources: incandescent lights, LEDs, mercury vapor lamps, halogen lamps, candles, wood fire, arc lamps, flourescent lamps, and the list goes on. None of them really produce a pure, even spectrum, and each one of the wavelengths it puts out interacts differently with different materials.

Then once it's produced by the light source, it has to deal with absorbsion (and re-emission as other colors), reflection, refraction, transmission, scattering, interference, and who knows what else. So when you mix two paints, you have to account for all those other things if you really want to know what color you're going to end up with. The thing the printing industry tries to do is simplify everything enough that they can reproduce most colors based on just a few, for practical reasons. Which is why we use primary colors. But that's definitely not the whole story.

So I hope you'll forgive me for make the vast simplifications to make the mixing of colors understandable and not overwhelming.

[capnhowdy]

Originally Posted by linknoid

As a physicist (well not really, but I did major in it in college for a while), I would say that you're correct (at least in this comment, the next one where you say to throw out the spectrum completely is going overboard). In my explanation I specifically avoided going into the complexities of perception or even the details of what happens when you mix color. The point was to explain the basics of how colors work to someone who claimed not to know hardly anything about it.

Each person's eyes respond to slightly different wavelengths. In fact, some men only see 2 shades (they're colorblind), and some women actually, because of genetic issues, have 4 types of cones instead of 3, and they actually see a much different colors (and they're genetics mean if they pass on the genes that produce 4 colors for them, their sons will be colorblind).

But once you get past the issue of how each person responds to the various (and infinite) combinations of the colors of the spectrum, then you have to deal with where that combination of wavelengths and intensities are coming from.

First you have the light source. Each different source is different. The sun produces a relatively complete visible spectrum, resulting in very white light, but by the time it's passed through the atmosphere, a lot of the blue end has been scattered out, and even then the spectrum changes based on the time of day, the weather conditions, the pollution in the air, etc. And there are many other different light sources: incandescent lights, LEDs, mercury vapor lamps, halogen lamps, candles, wood fire, arc lamps, flourescent lamps, and the list goes on. None of them really produce a pure, even spectrum, and each one of the wavelengths it puts out interacts differently with different materials.

Then once it's produced by the light source, it has to deal with absorbsion (and re-emission as other colors), reflection, refraction, transmission, scattering, interference, and who knows what else. So when you mix two paints, you have to account for all those other things if you really want to know what color you're going to end up with. The thing the printing industry tries to do is simplify everything enough that they can reproduce most colors based on just a few, for practical reasons. Which is why we use primary colors. But that's definitely not the whole story.

So I hope you'll forgive me for make the vast simplifications to make the mixing of colors understandable and not overwhelming.

Thanks for the input, Link...... highly informative. I must apologize as frequently my creativity and preference to the abstract bullheadedly ignore the facts and physics of almost any subject. You know what they say about us...ahem...artists. I'm still not sure if I have a talent or a curse. While I live in a world of imaginative creativity on a daily basis, I find it difficult at times to mindframe "the real deal". Thanks for the reality check. Please bear with me.........

[cweekly]

thanks for the clarifcation/correction, linknoid
(sorry xobruce, didn't mean to lead you astray)

so I do think I was right about the striations, but yeah was off base wrt the doppler effect's relevance to the colors. didn't quite jibe with me either, glad to get to the root of it.

"crippled but free, I was blind all the time I was learning to see..."

[xoxoxoBruce]

That's OK, cweekly. That's what we do here, run it up the flagpole and see if it gets shot at.