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Why is the sky blue?

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Re: Why is the sky blue?

#91

Post by lovecg »

margalabargala wrote: post #12
RupertSalt wrote: post #6

Obligatory xkcd: "Sky Color" https://m.xkcd.com/1145/ Obligatory xkcd[2]: "Rayleigh Scattering" https://m.xkcd.com/1818/ Others?

The "Rayleigh Scattering" comic is really spot on. Air is blue. The reason air is blue is blah blah blah physics, see the article we're all commenting on, but at the end of the day air is blue. We don't demand the same elaborate physics questions for why a ripe banana peel is yellow.

Though is some cases it is a very interesting question, like why gold and copper the color they are instead of being boring and silvery like all the other metals?

Re: Why is the sky blue?

#92

Post by jet98 »

smegger001 wrote: post #85
zkmon wrote: post #82

Okay, why does visible light have that range of frequencies?

because they are the frequencies that pass though water most readily, and we are made of mostly water

that's interesting. I thought it was because our sun's spectrum has the most energy in visible light band - therefore we evolved to see the light which can give us the highest SNR.

Can you be more specific?

Re: Why is the sky blue?

#93

Post by leeoniya »

SAI_Peregrinus wrote: post #78
leeoniya wrote: post #64

Earlier quoted context omitted.

i used something like this in unstructured technical interviews all the time. "you type a phrase into google search, you press enter, get some results. tell me, in technical detail, what happened in that chain of actions" the diversity of replies is fascinating, you learn a lot about a "full stack" candidate this way. Feynman's classic "Why?" chain: https://www.youtube.com/watch?v=36GT2zI8lVA

I'd probably spend at least 20 minutes just to get through how the keyboard works, much more if it's a USB-HID device.

the good ones would usually follow up with, "how much detail do you _really_ want ;D"

Re: Why is the sky blue?

#94

Post by asqueella »

awesomelybad wrote: post #79

Implementing an atmospheric shader in three.js is a fun way get an understanding of the interaction of the different scattering components, light, and observer’s position. Plus you get a pretty cool effect to play around with after you’re done.

The explanation that made it click for me a while ago was by someone who implemented a shader https://www.alanzucconi.com/2017/10/10/atmospheric-scatterin... — the explanations that don't end up producing an image all seemed to skip over one detail or another.

Re: Why is the sky blue?

#95

Post by Darkphibre »

I always loved this question when I played the 'Why' game with my kids: They ask why, and I'd ELI5. Then they'd ask why, and the process continued until I could excitedly say "We don't know for sure!! We think it might be XYZ, but we're still exploring that frontier."

Re: Why is the sky blue?

#96

Post by jjtheblunt »

amelius wrote: post #90
jjtheblunt wrote: post #32

Earlier quoted context omitted.

It's also the trick employed by Iridigm, which Qualcomm acquired in late 2004 (i was there then). https://en.wikipedia.org/wiki/Interferometric_modulator_disp...

I'm curious how they were able to patent a technique invented by nature millions of years ago.

the displays have an array of switchable mirrors individually addressable, unlike nature in this case.

(but sort of like chromophores in an octopus or cuttlefish, perhaps).

Re: Why is the sky blue?

#97

Post by erikdkennedy »

IshKebab wrote: post #88

If you think about it "because air is blue when you look at it from the side" is about all the explanation we'd require if the sky was some normal object like an apple. Nobody asks "why is wood brown?" as if it's some deep question, but "why is the sky blue?" is somehow given greater gravitas, as if the reason is more mystical. I guess because the sky is so big and uniform?

It could also be this sorta thought:

"There's air in my room, it appears transparent. The sky is made of air, it appears blue. Why the difference"

Re: Why is the sky blue?

#98

Post by seanalltogether »

justin_dash wrote: post #8

For the sunset example then, a natural question (for me) is then why isn't the sky green in the transition from blue sky to red sunset sky?

Blue + Green + Red = White

Green + Red = Yellow

Red = Red

That is the natural transition from overhead sun to sunset as each higher energy wavelength gets cut off more and more. When blue is mostly gone and green starts to fade we call it the Golden Hour.

Re: Why is the sky blue?

#99

Post by reactordev »

SAI_Peregrinus wrote: post #71
staplung wrote: post #18

In The Cuckoo's Egg Cliff Stoll recounts an episode from the oral defense of his astrophysics PhD thesis. A bunch of people ask questions but one prof holds back until... """ “I’ve got just one question, Cliff,” he says, carving his way through the Eberhard-Faber. “Why is the sky blue?” My mind is absolutely, profoundly blank. I have no idea. I look out the window at the sky with the primitive, uncomprehending wonder…

It also needs a bit of biology. Our eyes don't have a flat response over frequency, they're more sensitive to blue than violet. Violet gets scattered even more than blue, and the violet light does shift our perception of the color. But it does so less than it would if we had photoreceptors more sensitive to violet , so the resulting perceptual color depends not just on the intensity of the light at different frequenc…

The real question is, is the sky blue for everyone? Some creatures can see ultraviolet. Some lack color at all…

Re: Why is the sky blue?

#100

Post by reactordev »

brabel wrote: post #76
jstummbillig wrote: post #74

Earlier quoted context omitted.

I am positively excited about the upcoming first generation of humans who will have all their questions answered, correctly and in the way they can best understand, and as often and many of them as they want – and what that is going to enable.

The same anticipation of great things happening preceded the arrival of widely available internet, but all we really got was cat videos initially, and doomscrolling more recently. I don’t have much hope for great things anymore.

We got more than that. We got 24/7 surveillance.
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