Atmosphere colors showed in pictures

[Guest]

I've read an article about the colors of atmospheres in alien planets, and it was about the color of atmospheres based on their pressures.

A very thin atmosphere:


A thin atmosphere:


A normal atmosphere ( Earth-like atmosphere ):


A thick atmosphere:


A more thick atmosphere:


A super thick atmosphere:


A hiper thick atmosphere:


An extreme thick atmosphere:


I showed these images for you can have an idea on what I am talking about.

A planet with extreme thick atmosphere would be a planet between a rocky and gas giant planet.

[Evil Dr Ganymede]

IIRC the colour that you see on the ground depends in part on the gases in the atmosphere and how they scatter light, in part on how thick the atmosphere is, and in part on whether there's anything else (like dust) in the atmosphere.

I think any colouring effect would get more noticeable as the atmosphere thickens, yes. But at the same time, it'd get harder to see through the atmosphere because there's more clouds and stuff in the way. So unlike the pictures shown here, the sun would get dimmer with a thickening atmosphere, until it's a large bright patch in the sky, and then even that would disappear (if the atmosphere is thick enough all the light may be scattered over a huge area of sky or disappear completely)

And the martian sky is reddish, for example, because of particles of dust held aloft in the air. I'm not sure what colour it should be without the dust there, but it'd probably be a pretty dark colour since the atmosphere is so thin.

[granthutchison]

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[granthutchison]

Did you get this from http://www.orionsarm.com/whitepapers/sky_on_alien_worlds.html?
That site doesn't really make sense, since the author seems to forget that when an atmosphere is thick enough to scatter lots of red light, it is already maximally scattering blue light, and all longer wavelengths.
If you look towards the horizon on a clear day, you'll see what the sky would look like on a planet with >40 times the Earth's atmospheric density - white. Everything from 40 atmospheres to 1 atmosphere is visible if you scan from horizon to zenith - white, pale blue, blue. At lower atmospheric pressures, we can start to darken the blue towards black.

And that's all that's possible, for an atmosphere without the sort of particulates and/or preferential absorption the Evil Dr mentions.

Grant

[eburacum45]

I tend to agree with Grant; this particular essay will probably be revised in due course. The coulur of alien skies, where different to our own, will be more affected by the composition of the atmosphere and especially by particulates; blue and white seem to be the only colours you can really expect from Rayleigh scattering as such.
However I am sticking by the green colour of To'ul'h's atmosphere, as it is supposed to have an air-borne phytoplankton biosphere, giving the sky a green tinge in that way.

[eburacum45]

Here is another Orion's Arm world with a greenish sky; Doreen has an atmosphere rich in oxygen and chlorine, kept in dynamic equilibrium by a biosphere using two different types of photosynthesis, one of which produces chlorine gas.
Carbonate minerals are impossible on this world, so the sedimentary rocks contain vast amounts of reduced carbon, as coal. oil and kerogen.



John Dollan produced a very nice set of greenish yellow clouds for this very alien world; thanks, John.