Why don't nearby atmosphere look blue.

[A.T.]

So it means the bigger the air potion(atmosphere) we are looking at the larger the(number of) molecules scattering(or sending) the light(scattered light) towards us.

Yes. And to make it even more clear, one should talk about "looking through air", not "looking at air". The more air you are looking through, the more scattered light you will see from that direction.

 

[Ahsan Khan]

Yes. And to make it even more clear, one should talk about "looking through air", not "looking at air". The more air you are looking through, the more scattered light you will see from that direction.

Make sense

 

[sophiecentaur]

Hmmm great finally I got it. Well your last post gives me an opportunity to think," if there can be any situation which could make sky transparent( with colour effect neither white)? That could enable us to see the end of universe or our galaxy.

I do not put this question because of any doubt(about your reply or about science) it is just another related question(curiosity) that could shed more light on the nature of 'light' and our preception of 'light'.

That's Deep Space.

But don't forget relativity and the expanding Universe and a few other things!

 

[FactChecker]

A sudden epiphany. The sky scatters blue that you will not see directly unless you look at the sky. Suppose you are looking at a far-off mountain. The blue from the sky comes down to the lower atmosphere. Every foot of air between you and the mountain scatters a tiny amount of that blue towards your eye. So each foot of air is tinted blue a tiny, tiny bit. Put miles of air together and you start to see the blue tint. But here is an important point. It will still be much less blue than the sky. The blue is coming from the blue sky and can never be more blue than the sky, even if all the blue is directed at you. In fact, only a fraction is redirected toward you by the second scattering along the line of sight toward the mountains. So the blue tint of distant mountains will always be much less than the blue tint of the sky.

 

[sophiecentaur]

A sudden epiphany. The sky scatters blue that you will not see directly unless you look at the sky. Suppose you are looking at a far-off mountain. The blue from the sky comes down to the lower atmosphere. Every foot of air between you and the mountain scatters a tiny amount of that blue towards your eye. So each foot of air is tinted blue a tiny, tiny bit. Put miles of air together and you start to see the blue tint. But here is an important point. It will still be much less blue than the sky. The blue is coming from the blue sky and can never be more blue than the sky, even if all the blue is directed at you. In fact, only a fraction is redirected toward you by the second scattering along the line of sight toward the mountains. So the blue tint of distant mountains will always be much less than the blue tint of the sky.

Have you not read any of the preceding posts? You are implying that there is double scattering - once in the upper atmosphere and once in the air between your eye and the mountains. Does that make sense? I ask you, which is the greater source of light - the Sun or the proportion of the Sun's light that is scattered? Try looking at any of the thousands of web pages that explain what's happening - with diagrams.
Your explanation, above, misses the whole point. There may be 20km of air between you and the mountains. This will result 20km's worth of of the SUN'S DIRECT LIGHT being scattered and coming towards your eyes from that direction. This will add some bluish light to what comes from those mountains (reflected greens and browns, mainly). Compare this with the light coming from higher elevations, which has contributions from 100km or more of atmosphere with no reflecting objects behind it.


I think you need to be 'following that star' for a bit longer before you can considering that you've reached a true epiphany. Before you broadcast your conclusions, it might be a good idea to subject them to a bit of serious scrutiny by reference to all that readily available information.

 

[FactChecker]

"The effect of secondary scattering (you seem to keep ignoring this) is absolutely minimal and not part of this explanation. (1/1,000,000 X 1/1,000,000 = Nothing)"

You contend that the blue scattering of direct sunlight by the air in the line of sight to distant mountains is many orders of magnitude greater than the scattering of blue-tinted light coming from the blue sky. This is even though the blue sky provides a great deal of light and has more blue in it to be scattered. On a cloudy day it is common for photographers to use a warming filter that is not necessary otherwise. That leads me to believe that the color of ambient light from the sky is a larger factor than you are assuming. Maybe you have provided more supporting calculations in earlier replies. If so, I missed it. (P.S. One of the factors of 1/1,000,000 above is common to both the direct and indirect light and is misleading in comparisons of the two)

 

[sophiecentaur]

@ FactChecker: It is nice to be getting a well though out response on this thread. (I like the handle, btw; it makes me stand to attention, mentally.)
That factor of 1/million was probably an overstatement (I'm not sure) But you can go on the evidence of photographic experience. The difference between the reflected light from an object in full sun and in shade (in the absence of light cloud and other reflecting objects) is 'several stops' or a factor of a factor of 1/16 or less. That figure does't actually compare the intensity of light in a 1' solid angle from the Sun and from the sky - which is what I was getting at. The 'stops' figure is based on an integral and so I contend it is an underestimate. But I take your final point, to some extent.
If we assume you are right, and that the overall effect of scattered light from the sky, compared with direct sunlight, on any arbitrary volume of air, the ratio would still be a factor of 1/16, which can hardly be a significant modification of the perceived colour (subjective) of an already very de-saturated Blue. Either way, to me it seems to be a distractor and it is not valid to attribute the ' blueness' to 'blue coming down from the sky' and being scattered.

I am not sure how directly the practice of using a warming filter relates to this. I often tinker with the colour balance in cloudy and shady shots but I think that is due to the absence of the red from the obscured Sun, rather than to any extra blue from the clouds. That's a bit of an open question, I think. The fact that warm means cold and cold means hot, subjectively, doesn't help here. (lol)