[LotA] A flat world, a strange sun, and the resulting climate zones

[Jürgen Hubert]

From time to time, I'm working on a new setting with the working title "Legacy of the Annunaki". I won't go into too many details at the moment, but I'd like to share the work I've done on the climate zones so far.

The world is essentially a flat disc. Nothing unusual so far, but its source of heat and light is a sun which continually circles above the world. It follows a circular path which is about 2/3rds from the center to the rim of the world, and completes the path in a single day - in fact, that's how the locals define "day", since the sun never goes below the horizon. "Noon" is whenever the sun is closest to one's current position. The sun flies at a height of 1/6th the radius of its path.

I tried to calculate the heat energy reaching the world at its various positions, and this is the result of my calculations:



The colored bands represent the equivalents of heat energy reaching the surface of Earth at various latitudes (to be precise, at the spring and fall equinoxes). The outermost bands repesents 80°-90° latitude, the next band 70°-80°, and so forth. Eventually, the temperature bands get so close together that you can't distinguish them at this resolution (I may have to redo this with a higher resolution...). The innermost, yellow band actually gets more heat energy than the equator of Earth - up to 10% more at the center of the path of the sun.


However, this is only the original state of the world. The path of the sun is maintained by the six so-called "Pillars of the World", ancient artifacts built to keep the world stable and are located at equidistant points along the path of the sun. At one point during the history of the world, one of the pillars got destroyed. The nearby pillars compensated somewhat for its absence, but one of the end effects was that the sun vanished for approximately 1/12 of its path - thus creating the first "true night" the world has ever seen. This is how the climate zones shifted as a result:



A year ago before the official "start" of the setting, another pillar was destroyed, leading to yet another shift in climate:





That's what I've got so far. So, on a scale of 1 to 10 - how geeky do you rate it that I've actually calculated all this stuff?   ;)

[LD]

So what are the practical effects of the climate shifts?
New flora, fauna, etc?

The nearby pillars compensated somewhat for its absence, but one of the end effects was that the sun vanished for approximately 1/12 of its path - thus creating the first "true night" the world has ever seen. This is how the climate zones shifted as a result:

What is obscuring the sun?

When I imagine a disc, I wonder two things

1) if it itself rotates in any fashion; horizontally or vertically.

2) and would heating on the underside of the world have any background radiation to the opposite side. Thus, 40 degrees celsius in Australia would contribute a +2 degree to Alaska in the USA?

[Jürgen Hubert]

So what are the practical effects of the climate shifts?
New flora, fauna, etc?

Eventually yes - though first there's a massive die-off of the existing flora and fauna.

The nearby pillars compensated somewhat for its absence, but one of the end effects was that the sun vanished for approximately 1/12 of its path - thus creating the first "true night" the world has ever seen. This is how the climate zones shifted as a result:

Basically, the region has partially dissolved into the surrounding dimension - which could be considered "hyperspace" for all intents and purposes.

When I imagine a disc, I wonder two things

1) if it itself rotates in any fashion; horizontally or vertically.

2) and would heating on the underside of the world have any background radiation to the opposite side. Thus, 40 degrees celsius in Australia would contribute a +2 degree to Alaska in the USA?

In this case, the "underside" also connects directly to the surrounding dimension. This world is an artificial construct in an alien environment, so quite a few of the rules of the physical universe don't apply.

[LD]

Okay, well thank you and good luck!
~LD

[Ghostman]

This is pretty interesting. Originally I wanted to make my own setting into a flat world but gave up the thought due to too many problems with it. If you're going to tackle this concept and actually try and create an internally logical climate system, I wish you good luck with the attempt!

Here's some thoughts about your climate zones. I'm not trying to criticise your setting, just to point out some issues I think you should be aware of. It all assumes that physics work at least mostly similarly to real physics, ie. water runs downhill, freezes in below zero temps, etc.

[spoiler]As you said yourself, there was no such thing as actual night in the world before the first accident. This would mean that local flora and fauna (sentient races included!) would be accustomed to everlasting sunlight, which would make them very different from real world lifeforms(*). Perhaps no one ever sleeps?

(* Unless they all migrated from some other dimension in the first place.)

Another major factor would be the complete absense of seasons - unless you've got some way to add them in. In the RW we have seasons because our planet's axis is tilted relative to it's plane of orbit around the sun. There seems to be no similar mechanism in place in this flat world of yours, so presumably no seasons either. This is a very bad thing for the colder areas, as they'll never experience summer -  much needed for plants to grow and provide nutrition for the rest of the food chain.

In climates that are cold enough for snow to accumulate, there won't be much in terms of wildlife and even less people around. Unlike most cold climate zones of Earth, these would basically be massive glaciers locked in everlasting winter, with NO vegetation whatsoever, save for volcanic hotspots where there's enough heat from the soil to keep water in liquid form. Seas could remain unfrozen if the water is salty enough though, which would enable the existence of marine lifeforms and thus some birds and coastal land animals that live by preying on fish. Any sentiend beings would also be limited to sea coasts and volcanic "oases", being utterly unable to sustain themselves in the barren glaciers.

Your modeling of climate has only touched heat though, having said nothing about precipitation. How does rainfall work in this flat world? Is it's distribution uniform across the disc, random, or following some kind of pattern? If it's uniform, the world probably couldn't have any deserts at all.
[/spoiler]

[Jürgen Hubert]

This is pretty interesting. Originally I wanted to make my own setting into a flat world but gave up the thought due to too many problems with it. If you're going to tackle this concept and actually try and create an internally logical climate system, I wish you good luck with the attempt!

Here's some thoughts about your climate zones. I'm not trying to criticise your setting, just to point out some issues I think you should be aware of. It all assumes that physics work at least mostly similarly to real physics, ie. water runs downhill, freezes in below zero temps, etc.

As you said yourself, there was no such thing as actual night in the world before the first accident. This would mean that local flora and fauna (sentient races included!) would be accustomed to everlasting sunlight, which would make them very different from real world lifeforms(*). Perhaps no one ever sleeps?

(* Unless they all migrated from some other dimension in the first place.)

That's pretty much what happened, actually - the builders of this world (the Annunaki) snatched life forms from six different planets. Needless to say, different plants and animals have not adapted equally well...

Note, however, that while there used to be no true night before the destruction of the first pillar (and there was nothing accidental about it), for many regions there are still very significant differences in illumination and heat, depending on whether the sun is at its closest or its farthest position - the latter might be the equivalent of dawn or dusk.

Another major factor would be the complete absense of seasons - unless you've got some way to add them in. In the RW we have seasons because our planet's axis is tilted relative to it's plane of orbit around the sun. There seems to be no similar mechanism in place in this flat world of yours, so presumably no seasons either. This is a very bad thing for the colder areas, as they'll never experience summer -  much needed for plants to grow and provide nutrition for the rest of the food chain.

too[/i] complicated by varying the path of the sun...

Your modeling of climate has only touched heat though, having said nothing about precipitation. How does rainfall work in this flat world? Is it's distribution uniform across the disc, random, or following some kind of pattern? If it's uniform, the world probably couldn't have any deserts at all.

I'm going with the assumption that precipitation works similarly to Earth in its basic principles - heat causes steam to condense from the oceans, which in turn precipitates over land. But admittedly I haven't worked out the details yet...

[Ghostman]

I think I will just have the brightness of the sun vary by +/-20% over the course of the year. I don't want to make all this too complicated by varying the path of the sun...

That's a fine solution for simulating earth-like seasons, and avoids the problems that would come from adjusting the sun's altitude.

I'm going with the assumption that precipitation works similarly to Earth in its basic principles - heat causes steam to condense from the oceans, which in turn precipitates over land. But admittedly I haven't worked out the details yet...

The key thing here is wind. Without wind, the water would simply form into clouds directly over the seas from where it rose, and rain down on the same spot, thus doing nothing for overland areas. On Earth we have prevailing wind patterns caused by the rotation of the planet. Since your world is an artificially created disc, looking at Earth's wind system won't be much help though :-p You could probably just come up with an supernatural pattern for winds and consider it part of the way the world was created.

One tip though: wind doesn't have to blow in the same direction on the upper athmosphere as it does on the lower athmosphere. You could, for example, make the ground-level air (which is what people will experience and used to power windmills and sailing ships) move in an outward, clockwise spiral from the center of the disc to the edges, while the air higher up (where the clouds will be) moves in an inward, anticlockwise spiral from the edges to the center.