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[SOL] What % of Sunlight Is Blue or Green? [solar charts, answers in post #7]

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#1 Andrea B.

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Posted 05 June 2015 - 14:16

If anyone runs across the answer to this question, please let me know. Thanks!!

I have in my notes that sunlight is approximately 3% UV and 25-30% blue, but I don't where I got that from.

UPDATE: In Post #7 below I posted some answers to my question.
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#2 OlDoinyo

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Posted 05 June 2015 - 17:55

Perhaps this will help:

http://www.whyisthes...arradiation.gif

Judging by this, I would guess about half of visible flux is blue or green, but this plot is by wavelength rather than wave number, so that introduces a bit of complication--you cannot measure the area under this graph and get an answer.

#3 Andrea B.

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Posted 06 June 2015 - 14:16

Thanks, Clark. I have that chart but without the visible demarcations. This does help a bit.
Here is Clark's chart as a jpg in case the gif is not showing up in your browser.
Attached Image: solarradiation.jpg


I also found the following solar irradiance chart courtesy of http://www.pveducation.org/pvcdrom/p...ral-irradiance.
Here we can estimate the area under the curve w.r.t. UV and Vis ???

UV between 300-400nm is about 3 of those blocks.
Vis between 400-700nm is about 10 of those blocks.

But I can't find whether this chart is telling us how much reaches the earth (at sealevel, for example) or whether it is telling us what the sun is emitting. Given that I've read that the amount of UV reaching the earth is about 3% of the sun's output, I'd say that this chart must be the emission only.
ADDED: I may have been wrong about that 3% figure. See next post.
Attached Image: spectral-irradiance copy.jpg
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#4 Andrea B.

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Posted 06 June 2015 - 14:25

UV reaching earth's surface:
http://www.madsci.or...64750.En.r.html
The amount of UV radiation between 100 and 400 nm reaching the earth's surface is about 0.5% of the total amount of solar radiation reaching the earth's surface.


Composition of Sunlight: from Wikipedia Sunlight
Calculated from data in "Reference Solar Spectral Irradiance: Air Mass 1.5". National Renewable Energy Laboratory. Archived from the original on Sep 28, 2013. Retrieved 2009-11-12.
This is where I must have found my original statement about 3% UV. But preceding statement says that only 1/2% is between 100-400nm.
Sunlight at Earth's surface is approximately as follows. [So call it 4+42+54 = 100%.]
  • 3 to 5 percent ultraviolet (< 400 nm)
  • 42 to 43 percent visible (400 - 700 nm)
  • 52 to 55 percent infrared (> 700 nm)
Blue light reaching earth's surface:
http://www.reviewofo...essonid/109744/
The average proportion of blue light that's found in sunlight during the day is between 25% to 30%. Even on a cloudy day, up to 80% of the sun's UV rays can pass through the clouds.

Now how can blue light make up 25% of sunlight if only 42% of sunlight is visible wavelengths??? Hmmmmm. That only leaves 17% for green & red. This can't be right. I think they must mean that blue light makes up 25% of visible sunlight?


Bad Blue Light: 415-455nm
http://www.reviewofo...essonid/109744/
This bad blue light is more harmful to the eye's retina and RPE cells. Here are 415, 435, 455nm interpreted for the web as (118,0,237), (35,0,255) and (0,97,255).
Attached Image: BadBlue.jpg


Good Blue Light: 465-495nm
http://www.reviewofo...essonid/109744/
The good blue light is essential to our vision, the function of our pupillary reflex, and in general to human health. Here are 465, 480, 495nm interpreted for the web as (0,146,255), (0,213,255) and (0,255,203).
Attached Image: GoodBlue.jpg


Sky Blue Light: approximately 474-476nm but slightly unsaturated, i.e., mixed with white light.
Now we can correct our photographic blue skies!! :) And I'm certainly happy that Sky Blue Light falls into the category of Good Blue Light.
"Human color vision and the unsaturated blue color of the daytime sky", Glenn S. Smith, American Journal of Physics, Volume 73, Issue 7, pp. 590-597 (2005).
Here are 474, 475, 476nm interpreted for the web as (0,187,255), (0,192,255) and (0,196,255). These are more than halfway (0,128,255) between pure cyan (0,255,255) and pure blue (0,0,255).
Attached Image: blueSky.jpg


Human Eye Receptors: (approximate peak) 430, 545, 572 nm
From Wiki http://en.wikipedia....ki/Color_vision with reference to Wyszecki, Günther; Stiles, W.S. (1982). Color Science: Concepts and Methods, Quantitative Data and Formulae (2nd ed.). New York: Wiley Series in Pure and Applied Optics. ISBN 0-471-02106-7.
Well, this chart is surprising!!! I suppose I expected to see some version of red on the right.
Attached Image: HumanEyePeaks.jpg


Convert wavelength to RGB value:
http://academo.org/d...r-relationship/
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#5 msubees

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Posted 06 June 2015 - 14:46

Since we see the sunlight as "white", does not that tell us the proportion of various colors? more or less equal amounts of R, G and B? just a thought.

#6 Andrea B.

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Posted 06 June 2015 - 15:00

The human brain plays tricks. What we "see" as white may not actually be white.
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#7 Andrea B.

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Posted 06 June 2015 - 15:51

Composition of sunlight
I want to give full credit for the charts I am posting here.

From the Aquarium enthusiasts at Advanced Aquarist we have three articles. Ms. Riddle's references are the following.
  • American Public Health Association, 1998. Standard Methods for the Examination of Water and Wastewater. United Book Press, Maryland.
  • Bradner, H., undated. Attenuation of light in clear deep ocean water.
  • Hunt, R., 1998. Measuring Colour. Fountain Press, England. 344pp.
  • Jerlov, N., 1976. Marine Optics. Elsevier Press, Amsterdam.
  • Joshi, S., 2013. Equipment Review: LED Lighting Tests: Ecotech Radion Pro, Aqua Illumination Hydra, GHL Mitras 6100HV and 6200HV. http://www.advanceda...m/2013/8/review
  • Kirk, J., 2000. Light and Photosynthesis in Aquatic Ecosystems. Cambridge University Press, Cambridge, UK. 509 pp.

Dana Riddle's % breakdown of visible light from Table 1 in the 1st article.

Violet 4.98%
Blue 13.85%
Green-Blue 4.49%
Blue-Green 9.95%
*****
Green 9.98%
Yellow-Green 19.25%
Yellow 4.13%
*****
Orange 7.66%
Red 25.71%


Dana Riddle's pie chart of visible sunlight components from the 1st article.
Attached Image: SunlightPieChart.jpg


Dana Riddle definitions of visible bandwidths.
Keep in mind that this is not a standardized thing.
  • Violet: 400 - 430 nm
  • Blue: 431 - 480 nm
  • Green-Blue: 481 - 490 nm
  • Blue-Green: 491 - 510 nm
  • Green: 511 - 530 nm
  • Yellow-Green: 531 - 570 nm
  • Yellow: 571 - 580 nm
  • Orange: 581 - 600 nm
  • Red: 601 - 700 nm
Dana Riddle's bar chart of the visible sunlight components from the 1st article.
Attached Image: SunlightBarChart.jpg


Dana Riddle's chart of sunlight reaching earth from the 3rd article.
Keep in mind that atmosphere, time of year, time of day, elevation and other factors affect this kind of measurement. This chart includes UV and Infrared. Thus we can see an nice example of just how little UV reaches earth (in Hawaii anyway).

Sunlight quality under these conditions - 12:15pm, November 18, 2013, clear sky, 10 feet above sea level, Winds NNW @ 16mph, Humidity = 53%, Visibility = 10 miles. Vog (volcanic emission and smoke) = light. Kailua-Kona, Hawaii (19 39' 0" N, 155 59' 39" W)
Attached Image: SunlightAtSeaLevel.jpg
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#8 Andrea B.

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Posted 06 June 2015 - 16:39

Zach, after looking at the Pie Chart above, I'd say your speculation is approximately correct about equal amounts of R, G and B if we are willing to stretch the boundaries a bit for what constitutes R, G and B. :) :D :D
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#9 Andrea B.

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Posted 06 June 2015 - 17:12

Attempt at chart for Bee Vision peaks: 345, 440, 535nm.
535 = (112,255,0)
440 = (0,0,255)
The wavelength to RGB converter only goes as low as 380nm = (97,0,97).
So I'm very arbitrarily using (75,0,75) for 345nm.

Attached Image: BeePeaks.jpg
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#10 msubees

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Posted 08 June 2015 - 13:39

thank you! this is good to know :)

View PostAndrea B., on 06 June 2015 - 16:39, said:

Zach, after looking at the Pie Chart above, I'd say your speculation is approximately correct about equal amounts of R, G and B if we are willing to stretch the boundaries a bit for what constitutes R, G and B. :D :D :D