Colors of Twilight vs. Sunset/Sunrise

[Peter87]

All I can say is that purple light triggers a response from both the blue-sensitive and the red-sensitive rods in our retinas. Consider this color, ███. The (rgb) values of this particular color is, r = 123, g = 0, and b = 222. So purple, at least as far as our eyes are concerned, is indeed a mixture of red and blue.

I can see that the mixture of red and blue light in the sky under certain circumstances will make parts of even in the cloudless dawn or dusk sky look purple (because the atmosphere itself will reflect light and provide some mixing of the colors). I know I have seen clouds reflecting the dawn or dusk light look purple (but mixed with other colors as well).

I have seen the sky look like this. Credit: EIJI OGURA/EYEEM/GETTY IMAGES

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I have seen the sky look like this. Credit: I don't know.

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Ann

Ann, that’s very interesting to see the purple color with rgb values of r = 123, g = 0, and b = 222. The b = 222 is a high value -- approaching the maximum 255.

I am wondering how to describe the blue in the upper atmosphere behind the purple clouds in the first photo. It looks as if it is during blue hour. Do you think blue rgb values of blue hour would be lower than 222?

[Ann]

All I can say is that purple light triggers a response from both the blue-sensitive and the red-sensitive rods in our retinas. Consider this color, ███. The (rgb) values of this particular color is, r = 123, g = 0, and b = 222. So purple, at least as far as our eyes are concerned, is indeed a mixture of red and blue.

I can see that the mixture of red and blue light in the sky under certain circumstances will make parts of even in the cloudless dawn or dusk sky look purple (because the atmosphere itself will reflect light and provide some mixing of the colors). I know I have seen clouds reflecting the dawn or dusk light look purple (but mixed with other colors as well).

I have seen the sky look like this. Credit: EIJI OGURA/EYEEM/GETTY IMAGES

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I have seen the sky look like this. Credit: I don't know.

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Ann

Ann, that’s very interesting to see the purple color with rgb values of r = 123, g = 0, and b = 222. The b = 222 is a high value -- approaching the maximum 255.

I am wondering how to describe the blue in the upper atmosphere behind the purple clouds in the first photo. It looks as if it is during blue hour. Do you think blue rgb values of blue hour would be lower than 222?

I'm not sure that the picture taken by Eiji Ogura was taken during the blue hour. It might have been. I think it is more likely that the other picture was. The clouds reflected the colors of the reddened Sun after it had sunk below the horizon.

Wikipedia shows us this cloudless picture of the blue hour:

Praia da Ursa, Cabo da Roca, Portugal during the blue hour. Credit: Rnbc

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My guess is that the b value of the sky during the blue hour would be 255.


I found an interesting chart showing the hues, hex codes and rgb values for several shades of purple. There is always more b than r in all these shades of purple, and the b value is at or close to 255 in all the shades of purple except the darkest ones.

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Ann

[Chris Peterson]

Thanks for the suggestion, Chris, I didn't think of that!

That's a lovely goat, by the way. What's her name? She looks very feminine to me!

Ann

Gretel. She'll be kidding in a couple of weeks.

Thanks for teaching me a new word, Chris! I only knew one meaning of the word "kidding".

I'm sure Gretel's kids will be adorable!

Ann

[Ann]

Gretel. She'll be kidding in a couple of weeks.

Thanks for teaching me a new word, Chris! I only knew one meaning of the word "kidding".

I'm sure Gretel's kids will be adorable!

Ann

Click to view full size image

Oh no no no, I can't stand the cuteness of this baby! Is the little one a boy or a girl?

Couldn't find a good goat emoji, so I guess a unicorn is the closest thing!

Ann