I have been very appreciative of the Netflix series Altered Carbon especially thanks to scenes such as those taking place in the location called Aerium.

For those who aren't in the know, the Aerium would be a neighborhood of supertall skyscrapers rising above a heavily polluted city, reaching where the smog cannot, granting those rich or lucky enough to live there clear views and clean air.

I have been wondering what the conditions for such a scenario would be. How tall would the building need to be? How polluted is the air? And what about the weather patterns?

Here are the screenshots taken from the wiki:

enter image description here enter image description here

More elaborately, would it be possible for those dwelling at ground level to experience a grayscale sky even when there would be no clouds (due to considerable pollution and aerosols in the sky), while for those living on the upper floors of the building it would be blue and pristine? Could that be somehow achieved with a taller building?

  • $\begingroup$ A few remarks about the rainbows. The second picture shows a rainbow like an extended lens flare, looking into the sun. That does not happen in RL, refer physics.stackexchange.com/questions/315045/… you'll have to look away from the sun. And to get a rainbow above the clouds, in blue sky is inprobable: need a second cloud layer providing the drops a rainbow needs. Third remark: high contrast causes mirroring rainbows.. and mirrored mirrored rainbows (triple) A double rainbow has two rainbows with colors in opposite order, with a darker region in between. $\endgroup$
    – Goodies
    Commented Sep 5, 2021 at 18:39
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    $\begingroup$ Actually since that is an arc with red inside, you are technically correct, because that would be a sun dog, not a rainbow. I have seen them myself and the only anomaly is there seems to be less clouds than I would expect. The colors are not always there, but I have seen them. $\endgroup$
    – Mary
    Commented Sep 7, 2021 at 3:40

2 Answers 2


How tall would the building need to be? How polluted the air?

About four stories, and as polluted as London.

Parsons Brinckerhoff conducted a study on the effect of the change in air quality with height in London and Cardiff UK, measuring nitrogen dioxide concentration. They found:

The results show that air quality does indeed improve with height (mainly at roadside locations) up to the fourth floor of typical buildings. Beyond this a further reduction is minimal

An example of pollution sufficient to obscure vision would be the Great Smog of 1952. This is substantially thicker than that required to alter the colour of the sky:

Visibility could be down to a metre or so in the daytime. Walking out of doors became a matter of shuffling one's feet to feel for potential obstacles such as road kerbs. This was made even worse at night since each back street lamp at the time was fitted with an incandescent light bulb, which gave no penetrating light onto the pavement for pedestrians to see their feet or even a lamp post.

This was caused by a particular weather event (a temperature inversion) along with pollution, and extended much higher, 100-200 metres deep. One could choose any amount of pollution between these levels as fits the story.

NO2 by height Roadside NO2 diffusion tube monitoring with height in London and Cardiff. Each green point indicates the average monitored NO2 concentration for each floor and the red error bars indicate the minimum (left) and maximum (right) NO2 concentrations measured at each floor.

  • $\begingroup$ The 'grayscale' essentially means that there is enough fine particulate in the atmosphere that the incoming light from the star is interfered with so much that the sky looks gray rather than blue, even in the absence of clouds $\endgroup$ Commented Sep 5, 2021 at 13:52

You seem to be looking at not just a city based level of pollution, but a planet wide level of pollution - where the entire atmosphere is polluted so much that it blocks out much of the sunlight even without typical clouds.

So building skyscrapers really tall is a way around this.

To build skyscrapers you will need a solid foundation - they can't be built just anywhere, they need to be built on a solid layer of bedrock and ideally far from tectonic plate boundaries.

Definitely check out the geology that helps support the skyscrapers in New York.

In terms of how high these skyscrapers need to be to get the effect you want (judging by the screenshot you included), this depends on exactly how far up the polluted atmosphere reaches. There is a speculated maximum height for skyscrapers, but if you start going too tall you will run into problems with gravity and the spin of the planet, not to mention structural problems that might require you to invent some new wonder material to make it all feasible (eg the fictional material of adamantium). Carbon nanotubes might work, but currently we can't build a structure bigger than 1 metre with carbon nanotubes.

Something the size of the Burj Khalifa might do the trick - which stands 830 metres tall or 163 floors high.

Burj Khalifa

As you can see there are several other normal sized skyscrapers which are just dwarved by the Burj Khalifa. I am imagining a level of pollution that covers these smaller buildings, but the top half of the Burj Khalifa is poking out of the clouds, something like this (an actual photo of the Burj Khalifa while it was still under construction):

Burj Khalifa poking out of the clouds while it was still under construction

The thing that concerns me is the pollution.

You will need a delicate balance - too little pollution and you won't get what you are after but too much and the surface will be virtually uninhabitable. Too much pollution could end up making the whole planet incapable of sustaining the lives of the people living in the skyscrapers. In other words, so much pollution that there would be limited plant life and limited sea life - and this is where most of our oxygen comes from. This could easily be a dead world with that level of pollution.

You could have skyscrapers dedicated to farming to overcome this. If this appeals to you definitely have a look into vertical farming. But you would probably need half a dozen or more farming skyscrapers to support a single habitation skyscraper.

If this planet is part of a star travelling empire you could have orbital farming platforms in space or have regular deliveries of food from an agrarian planet. Having said this though, if you can have orbital farm platforms you can have orbital habitation platforms too - I don't see as removing the need for these huge skyscrapers, however you might want to rethink your social dynamic as the orbital platforms might be where the rich live and the poor live in the skyscrapers of the dead world below (and perhaps primitive wasteland tribes struggling to live on the surface outside the skyscrapers).

Polluting the planet this much would have severe consequences. But you still might get the effect you want with some tweaks.

First consider the idea that this polluted sky isn't permanent all year round - you could have a "smoggy" season where things are this bad but for the other three-quarters of the year the air is breathable and sunlight can reach the ground without issue. Still enough of a reason to build massive skyscrapers to get away from the smoggy season, but not so bad that it kills off all plant life on the surface of your world.

You could also use something other than pollution to get the effect you wanted. A huge series of dust storms that wrap around the planet might give you the "skyscrapers popping out of clouds" effect you want but without pollution. Plants would still suffer, but outside of the diminished light that reaches the surface, dust storms would be less damaging than actual pollution, which is usually toxic and harmful to all life.

An old planet (eg. several billion years older than our own planet) with only a small amount of water coverage and very little tectonic activity - a planet where all the mountains have been ground down by erosive forces - could easily create a world with lots of dust and high wind speeds that could give you a duststorm filled world. However, such a planet might not have a rotating liquid iron core that generates a magnetic field that our planet enjoys. Without a magnetic field the planet would be bombarded by radiation from space.

But to be honest whether an old world like this would have a spinning core or not (and what you could do about it if it didn't) is worthy of a separate question altogether.

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    $\begingroup$ Hmmm good point about the habitability concerns... the idea was that such levels of pollution would be concentrated only in some regions of the planet, while in others (most others) it would be relatively lower, lower enough to allow for industrial agriculture and an ecosystem capable of generating oxygen and maintaining overall habtability, I was thinking through the use of a pollution caputre technology/weather manipulation/localized terraforming. The landscape depicted would be the hallmark of the industrialized regions of the planet. Do you think that such a scenario would be possible? $\endgroup$ Commented Sep 7, 2021 at 7:13
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    $\begingroup$ @JuimyTheHyena Yes, given the scenario you've described I don't think pollution will be such a problem as to render the surface uninhabitable - instead these industrial areas will be habitable to those who have sufficient protective gear (like masks or air filtration systems in their buildings) to survive in the thick smog. $\endgroup$
    – Jimmery
    Commented Sep 8, 2021 at 3:31
  • $\begingroup$ Jimmery Perfection! Thank you very much I'll consider this settled then. $\endgroup$ Commented Sep 8, 2021 at 9:01
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    $\begingroup$ @JuimyTheHyena did I lose the tick? $\endgroup$
    – Jimmery
    Commented Sep 18, 2021 at 13:49
  • $\begingroup$ Oh hello...well...after closer inspection, the first answer is a bit more resolutive. Though if I have to be honest, if I could I'd say that a combination of both answers would be the perfect resolution especially what you mentioned in the comments. I'll see to make it up for you. $\endgroup$ Commented Sep 18, 2021 at 15:28

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