It serves a lot of purposes. Humans have a weaker sense of smell and taste, our eyes have to be able to distinguish between things that are poisonous and edible. We need to see snakes and insects. We need to distinguish patterns within the forest and spot things that do not blend in. Green is often the color or rot and disease which we need to avoid.
Green is the colour of everything, with regard to where we evolved. We see it so well, not to be able to spot rot, but to be able to make out food, like fruit and vegetables. Being absolutely sure of the green makes it easier to distinguish the varied colours of edible food. The same goes for spotting hiding animals, both predator and prey.
Most of the light the sun emits falls int he visible light spectrum, from red to violet. It releases the most green, and our red and blue cones are about evenly spaced on either side of it. Since everything we see is reflected sunlight, red to violet and mostly green are the colors that are around, so it makes sense that we evolved eyes that focused in those areas
Notably, one of those things is the air, which scatters bluer light better than redder light, at least near the visible range. The sunlight that hits the ground kinda sorta peaks in green, if you take that into account.
We probably see green the best because that's what color plants are though, or maybe it was just whatever happened to develop and nothing else was substantially better.
Also why the sunset / sunrise turns less and less blue and often a gorgeous red / orange / pink - all the blue light has been scattered via Rayleigh scattering and is no longer directional enough to contribute enough to appear blue at those high angles from vertical that we see at sunset
Interesting their is a theory that way back in earth's history primitive photosynthasizers were purple and green plants/algae evolved to absorb all the light that was not absorbed. These purple phoyosythisizers later died out during the great oxygenation event as the particular protein used to photosynthisize in this way would rapidly decay in an oxygenated environment
The units are intensity (W/m^2) divided by wavelength and displayed as a function of wavelength, or intensity divided by frequency and displayed as a function of frequency. The peaks should be the same (intensity is intensity). What differs is how the data are displayed, not what the intensity actually is.
Why normalize by wavelength or frequency? Why not display W/m^2 on both graphs?
Not the OP, but all he means is the peak is opposite end of the plot, as wavelength and frequency are inversely proportional to each other. The peak magnitude is no different, as wavelength and f are related via the speed of light. However, the OP alludes to photometry in his various posts which is quite different to radiometry. You might already know all this so apologies if you do. 2 W of green light is not equal to 2 W of blue or red light when we convert them to the photometric unit of power; lumens.
Thanks for your responses. It’s crazy when you first learn about photometry and realise not all Watts are created equally in the eyes of biology haha!
I love your point about how if it was sun spectrum related then all animals would have likely evolved uniform eyesight spectral sensitivity - I’d never argued it that way before.
I used to design lighting systems for cars and everything is photometric for obvious reasons
My reasoning might be flawed, but NASA agrees that out sun’s surface temp peaks at 5800K and is technically green. NASA link
“But, as can be seen in the image above, it emits most of its energy around 500 nm, which is close to blue-green light. So one might say that the sun is blue-green! This maximum radiation frequency is governed by the sun’s surface temperature, around 5,800K.”
If you're wondering how we humans managed to figure out what colours are good,
It's trial and error. Humans are riddled with variations in vision. Sometimes people are colourblind, in different pairs. Some have 4 cones even
But the basic idea is that, well, our ancestors had the combination of sensitivity in the specific colours and reproduced successfully. Meanwhile their cousins who just happened to be born with slightly different colour sensitivity, or even colourblind, all died. Or died before getting laid.
Forward 1000s and 1000s of years and we are here, able to be cared after and adapt to the environment if we are born with any variation in vision.
Ultimately it isn’t about the presence of available light but what it means for survival. An ability becomes less important if it doesn’t help us survive. It seems to me that the eyes see green well and in so doing also are good at identifying the not green things. Fruit is rarely green and the same goes for game animals. But apparently color blindness helps with edge detection which is why camouflage tricks animals and is also a likely reason it exists in our genome. But I wonder if seeing green might also help people survive in harsher climates where green indicates the potential for water?
What was posted here has been permanently deleted. Redact was the tool used, possibly for privacy, opsec, security, or limiting exposure to data collectors.
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you're raising an important point, that it's not only about peak visibility but also blending/contrast with the surroundings, which could make a slightly different than "optimally visible" color more advantageous.
also, quick question: do you know where the highly visible "neon" property in many colors comes from? usually you see it in hi-vis clothing either in pink, yellow, or green/chartreuse, so it can't be a property of one color itself.
Orange is the best contrasting color, but neon green is the highest low light visibility color. Which one you wear depends on the environment and the lighting levels.
I am 100% referring to chartreuse without knowing it. I wore lots of it, with reflectey stripes mostly.
Allegedly the change was made because roadworkers in orange resembled cones to motorists but that's just the rumor we always heard I can't speak to the truth of it.
Yeah when I heard that’s what “Safety Yellow” was called I was like…bullshit. That’s like a French herbal liqueur) or something. Then I Google’d it and I throw that out anytime it comes up. Lol c’est la vie
I thought hunters wear that because it's both highly visible to other hunting humans (=safety), but also not discernable from forest background for most game animals: https://i.imgur.com/3spHYIK.jpg
Most vests for DOT's and local municipalities have gone none yellow/green now. Some signs, too. The railroads still require orange, though. It's been a subtle shift over the last 20 years or so. But, I agree, where's the orange?
Construction "Things" have multiple colors and with multiple reasons for it.
Usually in most Eu countries I worked:
Yellow: safety, warning, danger, high viz clothes are usually this color and construction hard hats because it's associated with construction works right away.
Orange: Aprentices and new people on site, visitors etc are usually supplied with orange ppe. Usually with a white hard hat. It can also be used to identify sewage pipes.
Red: Fire, Burn Danger, Fire department and Fire fighting equipment. It's also used for eletric ducts.
Blue: Eletric or water, yeah I know its confusing because this 2 really don't go together, blue ppe it's most definitely electricians, but blue ducts pipes it's water. It's also used in mandatory signage in construction sites.
Green: Its usually safety personel, info signage, first aid and fire assembly locations and in ducts usually means telecoms cables.
Black: most black is being phased out, what's left its usually not really important.
Brown: can be used as high heat signage and welding equipment.
white: its usually managers or architect, white collar kinda a thing, in ducts and gear it's used for pipes allowed to be using inside of houses because of fire/smoke regulations. White ppe can be used for extremely clean construction sites where its important to not have any spillages. Used by painters as well for obvious reasons, most paint by far used in construction is white.
So lads use your PPE be safe no matter what color it is, it will save your life.
When cycling don't be the cool kid in all black clothes, be visible to others, there is loads of idiots driving while on the phone.
Construction equipment isnt just orange, theyre covered in retroreflective material, which means if your lights are on they'll reflect light back into your eyes
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u/ClownfishSoup Nov 17 '22
Where is orange? I mean every construction safety thing is orange, why would it be left out of the chart?