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Old 09-17-2017, 11:20 AM   #1
muduri
 
Join Date: Oct 2009
Location: Alphabet City, New York
Default scripts for generating climate from topography

The characters in my fantasy campaign haven't made it out of a small corner of the world yet, and before they do I'd like to do a better job of matching topography and climate. I'm thinking of creating (or better yet, just using, if one exists already) a script to take a topographic surface, apply wind and ocean current patterns to it, and then derive climate.

1) Does such a thing exist already? Looking online I see several scripts that generate everything procedurally from scratch, but not one that lets you input your own topography. Part of the appeal of course is that you could work back and forth - "ah, we need a savanna kingdom here surrounded by rainforest hunter-gatherers. Time to reverse the slope and create a Dahomey Gap!"

2) Does three variables (average temperature, summer rainfall, winter rainfall) sound like the right amount to generate climate? I was originally planning to unify rainfall anually but it seems like Italy's vegetation is distinct from the American Southeast partly because of dry vs wet summers. I suppose though that one would have to introduce some intermediate factors like pressure before yielding something emergent like an ITCZ.

3) Programming language considerations? I get the impression a bunch of you are talented programmers; for better or worse, coming from architecture I'd be working more from Adobe/Rhino/Grasshopper/Ladybug, which if nothing else I guess should be helpful for the topography manipulation. But could cobble together just enough scripting to use something else if it called for modifying an existing procedure or there was something that just couldn't be done in Grasshopper.

Any suggestions on these, or any other follow-up thoughts, welcome! Happy to share the script when it's done also. Thanks!
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Old 09-17-2017, 12:05 PM   #2
whswhs
 
Join Date: Jun 2005
Default Re: scripts for generating climate from topography

My old ecology textbook had a triangular diagram of climates, with the extremes being glaciated, dry hot desert, and rain forest. You could generate that with two variables, if you allow for the fact that both latitude and altitude influence temperature. But seasonality is important; dry summer climates like California, Greece, or parts of Chile are quite different from wet summer climates with the same total rainfall and comparable temperature. (On the other hand, I'm not sure you do get both the same; east coast places at the same latitude as San Diego get a lot more rain, don't they?) So your three variables are a good start.

The second level, though, is that you want to look at wind patterns. For example, do you have a planet with three wind circulation zones, like Earth? Or one with one, or five, or even some huge number like Jupiter? (This is fantasy; you can have unrealistic planetary physics!) And you want to take into account the rain shadows of mountains.

But I know little about programming, and even less about software. I did my last world design by eyeballing.

What I want is a program that will let me define tectonic plates and project terrains.
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Old 09-17-2017, 01:01 PM   #3
mlangsdorf
 
Join Date: Aug 2004
Location: Austin, TX
Default Re: scripts for generating climate from topography

The Koppen climate classifications (https://en.wikipedia.org/wiki/K%C3%B...classification) are based on distribution of monthly temperature and monthly rainfall. Even then, the climate types are fairly inclusive, with all of the southeast US (for instance) being in the same climate. I've lived in San Antonio TX and Washington DC and while they may both be humid subtropical climates, there's pretty substantial variation between them.

I think you need at least average temperature, season temperature variation, and monthly rainfall (summer vs winter isn't appropriate for climates with dry and monsoon seasons).

I also suspect you're creating unnecessary work for yourself. Climate is weird and affected by a lot of things beyond obvious geography, like wind patterns, jet streams, and ocean currents. For instance, England is as far north as most of Canada, and should be a subarctic climate (based on its latitude), but it's actually a humid subtropical climate. You can just eyeball climates and/or adjust them for story reasons, and no one is likely to mind or possibly even notice.

My experience is that if you eyeball climates and provide some basic justifications for any apparent anomalies, people will go with it. Just pick what you like or roll randomly. Figuring out daily weather patterns will make more difference in your game, and you can roll randomly on a table and get acceptable results for daily weather.
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Old 09-17-2017, 01:17 PM   #4
Crystalline_Entity
 
Join Date: Jul 2015
Location: England
Default Re: scripts for generating climate from topography

I think the Holdridge life zones diagram (which I think is what whswhs is referring to?) might help:

https://en.wikipedia.org/wiki/Holdridge_life_zones

I think coming up with a plausible script to generate climate would be an awful lot of work - just off the top of my head, the variables would include latitude, the number of atmospheric circulation cells, length of a day, axial tilt of the planet, distribution of land and water, and that's just to get the broad-scale atmospheric and oceanic circulation before getting into the specifics of a given location. I think Fractal Terrains 3 could try and work out climate, but I'm not sure how good the algorithm it uses is, it might be fairly simplistic.

Maybe you could work out the general trend for the region (e.g. Is it a warm or cold ocean current by the coast? What is the prevailing wind direction? Am I in the rainshadow of a mountain) then just handwave the local details with something which sounds plausible.
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Old 09-17-2017, 02:23 PM   #5
whswhs
 
Join Date: Jun 2005
Default Re: scripts for generating climate from topography

Quote:
Originally Posted by Crystalline_Entity View Post
I think the Holdridge life zones diagram (which I think is what whswhs is referring to?) might help:

https://en.wikipedia.org/wiki/Holdridge_life_zones
Yes, that's the diagram I remember from Odum.
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