Why do Aurora colors in a bottle resemble Aurora Australis?

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Discussion Overview

The discussion revolves around the similarities and differences between the colors observed in auroras, specifically comparing the Aurora Borealis and Aurora Australis, as well as the colors produced in a related experimental demonstration. Participants explore the reasons behind the changing colors in auroras and the factors influencing these variations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that the colors in the experiment resemble Aurora Australis, questioning the basis for this classification.
  • There is a discussion about the ionization of oxygen and nitrogen atoms in real auroras, which primarily produce red and green colors, and how these mix to create other colors like purple and yellow.
  • One participant notes their personal experience with auroras, stating that they have predominantly seen green in Aurora Borealis and purple in Aurora Australis, raising questions about the differences in color representation.
  • Another participant argues that while purple is observed, it is relatively rare and typically appears only during intense displays, with green being the primary color for both auroras.
  • There is a claim that there is no real difference in the auroras seen at each pole, as the nitrogen and oxygen composition of the atmosphere is the same in both hemispheres.
  • One participant discusses how the perceived color differences may be influenced by human vision, camera technology, and display screens, suggesting that these factors contribute to the variability in color perception.

Areas of Agreement / Disagreement

Participants express differing views on the typical colors of auroras and the factors influencing these colors. While some agree on the similarities in atmospheric composition and the resulting light emissions, others highlight personal observations that suggest variability in color representation.

Contextual Notes

Participants mention the influence of light levels on color perception and the technical aspects of color discrimination in imaging, indicating that these factors may complicate the understanding of aurora colors.

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Solomei said:
I would say that this looks more like Aurora Australis.

what makes you say that ? it clearly stated who took the photo and where it was taken

Solomei said:
What is the reason for these changing colors?

the changing colours ... in the real aurora foto or in that experiment ?

In a real aurora, it is mainly the oxygen and nitrogen atoms getting ionised and creating their specific colours, mostly red and green
those colours then mix to produce other colours that are seen ... purples, yellow, sometimes bluesDave
 
davenn said:
what makes you say that ? it clearly stated who took the photo and where it was taken
the changing colours ... in the real aurora foto or in that experiment ?

In a real aurora, it is mainly the oxygen and nitrogen atoms getting ionised and creating their specific colours, mostly red and green
those colours then mix to produce other colours that are seen ... purples, yellow, sometimes bluesDave
Im trying to figure this out. I know that aurora appears in different colours as you mentioned. I've seen aurora borealis many times, and it has always been green. I've also seen pictures of aurora australis which has manly been purple. Why do they then refer to this experiment as the northern lights, when it is more typically the colours for the aurora australis? What exactly makes the difference for these lights beside that they appear on the northern and southern hemisphere? Is it a big (constant) difference in gas concentrations above each of the poles that effects the spectrum?
 
Solomei said:
Ive also seen pictures of aurora australis which has manly been purple.

that wouldn't be the norm, rather relatively rare. Only in the really intense displays would purples start to show ...
Aurora Australis is also primarily green and as the activity intensifies, the reds show, then the yellows and so on

here's are typical AA from my personal collection, This is from Dunedin, New Zealand

9811_au2.jpg


9811_au5.jpg


I do have some with colour trending towards purple, but these 2 pic's make my point :smile:

Solomei said:
What exactly makes the difference for these lights beside that they appear on the northern and southern hemisphere? Is it a big (constant) difference in gas concentrations above each of the poles that effects the spectrum?

there is no real difference between the aurora seen at each pole

Dave
 
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Davenn is right.
Since the nitrogen and oxygen composition of the atmosphere is the same in both the northern and southern hemispheres, and the charged particles are exactly the same, one would expect the light to be identical.

To human eyes, the colour will always be a false colour since the three different broad-band colour sensors in our eyes are being stimulated by narrow band emissions.

The apparent colour differences will be due to the variable ability of the eye to see colour at low light levels, by the type of colour discrimination used in the camera that records the image, or by the screen used to regenerate the image, before it is first viewed by human eyes.
 
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