Eli5 Why are most street lights and car lights orangish yellow and not white?
In: Technology
Many street lights were/are sodium vapor lights. It’s a highly efficient light that just produces a warmer light as the byproduct.
https://en.m.wikipedia.org/wiki/Sodium-vapor_lamp
Technology Connections made a great video on this subject.
[https://www.youtube.com/watch?v=U1dMlVwUsrA](https://www.youtube.com/watch?v=U1dMlVwUsrA)
TLDW, street lights are sodium lights that produce orange light, and there hasn’t been a good alternative until recently.
White does not work in fog very well. Yellow cuts through it easily. It’s not the only reason but it certainly helps.
This has do with the type of lamp used and what “Color Temperature” https://en.wikipedia.org/wiki/Color_temperature
you have for output. The various colors of “white” light can affect your moods and work to light areas better or worse depending on atmospheric conditions( fog, water vapor, humidity,etc) along with physical charactics of the surface being illuminated.
Yes this will be long, Light is Artistic medium that can be manipulated to make you see, feel and help you believe what you are seeing is real due to the shadows and light. Read on if you want to learn more, plus I can make you see colors that clearly aren’t there, with your eyes closed. But only if you read and learn below.
A Photo/TV show shot at night may have sunlight coming through a window created by stage lighting. There may not even be window at all but have a “GOBO” https://en.wikipedia.org/wiki/Gobo_(lighting) that interrupts the light creating shadows to give the appearance of window frame or perhaps subway grating or light coming through the trees day or night…. Lighting by shadows is a professional Craft.
First section **”Types”** has chart listing the different colors by lamp source. https://en.wikipedia.org/wiki/Electric_light
Light is the opposite of pigment colors you are taught in school . White is all colors and black is the absence of any color. What you see in pigements is really reflected light back at you, it absorbs all the light colors that you don’t see, red surface is reflecting back mainly red light waves. When in school you mixed all the paints/crayons you would get black and with out them you have white blank page. In Lighting Pure light is white and contains all the colors while Black is absent of any light. **A Prism will show you the colors** https://en.wikipedia.org/wiki/Prism
Take Blue light which is produced in two ways by Color Temperature (Bluish white you don’t want to directly look at from welding Arc or Xenon Arcs) and and color filter placed in front of the light source which absorb/block all the electromagnetic light energies other than color wavelength of blue ( infra-red red Orange Yellow, Green, Blue, Ingo Violet ultra-violate ) . That is called https://en.wikipedia.org/wiki/Color_gel used in the entertainment industry theater, dance, concerts,. film, TV etc. Which to Blend shooting in various shades of sunlight and different sources of light during day and night you enter into https://en.wikipedia.org/wiki/Color_correction which is to make your street lights appear to be all the same Amber/ Yellow light even if their real source is different “” tinted”” white light
Look at pictures on showing you the contrast of different filters same image
Look at https://en.wikipedia.org/wiki/Photographic_filter for examples of altered light.
Let me best explain it with picture/comic from XKCD
https://xkcd.com/273/
**Picture explaining what is Light**
https://imgs.xkcd.com/comics/electromagnetic_spectrum.png
and because XKCD is comic about science, love and mathematics there is fan based explanation guide to ever comic in case you need help understanding them
https://www.explainxkcd.com/wiki/index.php/273:_Electromagnetic_Spectrum
**So all that you see and all that you hear (Pink Floyd was right by the way) is the smallest fraction of the ElectroMagnetic Spectrum Frequency.**
To blow you mind a little more, there are people with a “disorder” called https://en.wikipedia.org/wiki/Chromesthesia which falls under https://en.wikipedia.org/wiki/Synesthesia which they see sounds as flashes of colors. They eyes respond to sound waves frequencies which are in two separate groupings on the Electromagnetic Spectrum . Church bells ringing would cause waves of color to fill their vision.
**Wanna see how those eye nerves work? Close your eyes and gently rub them. Did you “see” any flashes of light with your eyes closed? Surely you couldn’t “”see”” now could/did you….Yet those nerves were stimulated and sent off signals to the brain and the brain said they were colors and this where you sensed them at being…. Cool or scary you’re choice.**
To sum up what you’re missing, I’m going to quote from BattleStar Galactica(re-imaged 2003-2009) in Season 4 where one of humanized versions of cylon robots is so mad and upset about limits of his human eyeballs.
On youtube https://youtu.be/mPnx3zO3SDc?t=73 just jumping in a few seconds of when the quote below starts.
Number One aka Brother Cavil:
In all your travels, have you ever seen a star go supernova?
Ellen Tigh:
No.
Number One:
No? Well, I have. I saw a star explode and send out the building blocks of the Universe. Other stars, other planets and eventually other life. A supernova! Creation itself! I was there.** I wanted to see it and be part of the moment. And you know how I perceived one of the most glorious events in the universe? With these ridiculous gelatinous orbs in my skull! With eyes designed to perceive only a tiny fraction of the EM spectrum. With ears designed only to hear vibrations in the air.**
Ellen Tigh:
The five of us designed you to be as human as possible.
Number One:
**I don’t want to be human! I want to see gamma rays! I want to hear X-rays! And I – I want to – I want to smell dark matter! Do you see the absurdity of what I am? I can’t even express these things properly because I have – I have to conceptualize complex ideas in this stupid limiting spoken language! But I know I want to reach out with something other than these prehensile paws; and feel the solar wind of a supernova flowing over me. I’m a machine, and I can know much more. I can experience so much more. But I’m trapped in this absurd body**. And why?! Because my five creators thought that “God” wanted it that way.
So looking back at the XKCD comic/drawing and think about how much of that light/ElectroMagnetic Energy Spectrum you did not see/hear/feel flowing around you…… Those are the waves we know about, image finding out another set or style exists and what we could learn from them about what we thought we knew about the world around us. Those street light colors is tip of a very huge iceberg of vision science and the Art of Lighting.
Orange light does a great job at reflecting and travelling, the only problem with sodium lights is that they are expensive. In the UK (North Scotland, where I am), they have started to replace the lights with a white light, these are cheaper to run but do not light up the area as effectively as the orange light.
Hope this helps!
It’s a coincidence that Street Lights and car lights have similar colors. Street lights are the color of whatever technology is best(cheapest) at the time. In the 70’s it was White/Blue from the mercury vapor lights. I can still remember the complaints about the new orange lights, and having to wear sunglasses to drive down main street at at night.
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