Uncovering the Mystery of Why the Sky Isn't Green

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Discussion Overview

The discussion revolves around the reasons why the sky is not green, focusing on the scattering of light in the atmosphere and the observed colors of the sky at different times of day. It includes theoretical explanations, observations, and specific phenomena related to atmospheric optics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant claims the sky is blue due to the scattering of white light, specifically that blue light is diffused more than other colors, leading to a blue sky during the day and red/orange skies at sunset.
  • Another participant suggests that there is typically more red or blue light reaching an observer, with lower wavelengths diffracting more forward than higher wavelengths, which may explain the colors seen at sunset.
  • A participant shares a link to an image of a green sunset, implying that such occurrences can happen.
  • One participant mentions the phenomenon of the green flash, which occurs shortly after sunset or before sunrise, where the sky can appear green for a brief moment.
  • Another participant challenges the idea that the longer path of light at sunset leads to red scattering, arguing that the presence of other light sources (like clouds and haze) contributes to the observed colors.

Areas of Agreement / Disagreement

Participants express differing views on the reasons behind the colors of the sky, particularly regarding the effects of light scattering and the conditions that lead to the observed colors at different times of day. No consensus is reached on the explanations provided.

Contextual Notes

Some claims depend on specific assumptions about light scattering and atmospheric conditions, which are not fully explored or agreed upon in the discussion.

Ryan Lucas
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The sky is blue because the white light is diffused by the light particles, which scatter out the blue end of the spectrum, hense a blue sky. In the afternoon, it is often red or orange, because the light has to travel much longer through the atmosphere, scattering out the red end of the spectrum. Why then, between these two times, when the depth of the atmosphere through which the light travels increases, does our sky not change from colour to colour through the spectrum, from blue to orange? Why isn't the sky green?
 
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The way I see it is that there will always be more red light reaching you directly than any other colour of the spectrum, and likewise there will be more blue diffracted light reaching you than any other colour. One of these two will normally dominate over the other colours. If I remember my atmosphere lectures right, lower wavelengths are more prone to diffract forwards, than higher wavelenghts that scatter more evenly, so this explains the orange sky around sunset.
Anyway, I don't know about you but I've seen some pretty nice turquoises around sunset.
 
http://www.squamish.ca/PublicDownloads/DistrictPhotoLibrary/Wallpaper/GreenSunset.jpg for instance.
 
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There is a phenomena known as the green flash that actually occurs shortly after sunset or before sunrise, where the sky is briefly green.
 
369025833_4eea643719_z.jpg
 
fringepringe said:
There is a phenomena known as the green flash that actually occurs shortly after sunset or before sunrise, where the sky is briefly green.
This thread has been dead for 6 years. Congrats.
 
Ryan Lucas said:
In the afternoon, it is often red or orange, because the light has to travel much longer through the atmosphere, scattering out the red end of the spectrum.
If the sky scatters blue light the sky scatters blue light. Period. Making the path longer won't make it scatter red. What happens at sunset is that you start seeing light fromthe other things besides just the sun and empty sky (clouds and haze), through a lot of sky. The light from everything you see near the sun at sunset is thus nearly absent blue light.
 

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