# Mapmaking Discussion & Philosophy (WIP/Critique) > Regional/World Mapping >  Terraformed Venus

## acrosome

EDIT--  

Before you waste your time, I have changed the elevation data set that I was using and re-started several times.  If you want to see the current status of the map it starts on page 10.

--END EDIT

Howdy, All.

As I mentioned elsewhere my pet project is going to be a terraformed Venus.  I plan to use it for an ultra-low fantasy (no magic) campaign set a few millennia after a cataclysm.  Here's a preview:



This is a USGS topo map of the planet with a sea mask and 5-degree lat/long lines superimposed, Mercator projection, and it only goes to 57-degrees north and south.  (At the equator a 5x5-degree quad is roughly 328 miles square, so almost 108,000 sq miles- just a bit bigger than Colorado.)  It also is compressed quite a bit so that I could post it here- the original is over 27000 px across.  I'm going to use this to guide my work on smaller regional maps.  I'll also use this to figure out climate.

As a bit of a warning- It'll probably take me _years_ to get any work done on this, so don't expect updates often.

Here are the prevailing winds, before I take into account the continents:



If it looks backwards, remember that Venus rotates the other way- the sun rises in the west.

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## foremost

Sounds like a very neat idea  :Smile: 
Excellent detail of all the little islands, looks like back-breaking work.
Are those mountains or swamps?
No pressure on updating quickly, but when you get things done, please do let us know.

FM

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## acrosome

They are mountains (real planetology).  I'm _not_ planning on going with the classic "Venus as a swamp-planet" motif.

And on another forum someone just pointed out that I could rotate the map 180 degrees to disguise the fact that the sun rises in the west, to confound those who might otherwise recognize it.  Hmm.

Overview:



Prevailing Winds:



I'll presume that the Powers That Be decided to just designate east as "the direction the planet spins," and north is "to your left when facing east," etc.  The actual magnetic character of the poles really should have little to do with such things.

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## gilgamec

As part of the terraforming process, has Venus's rotation been sped up?  Otherwise, a single day will last so long (240 Earth days or something) that I'm not sure that you can use Earth-based climatic theory.  For example, the "day side" of the planet would be receiving light and heat for (Earth-)months at a time, so pressure zones that would form would be more based on continent/ocean size than axial inclination.

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## acrosome

Yes, I'm proposing that the rotation is sped up.  116-day solar days are pretty unworkable.  Speeding up Venus's rotation will deform it into a more oblate spheroid- it will bulge at the equator, causing new rifting perpendicular to the equator.  This will be roughly 40 miles of extra circumference, so I figured I'd add a new 2-mile rift every 20 degrees or so, plus lesser ones where needed.  (This actually gives me a way to drain some basins that would otherwise be inland seas.)

I'm also giving it 20-degrees or so of axial tilt, to generate seasons.

What I _haven't_ decided is whether I'll keep Venus in the same orbit with some sort of sunshade or if I'll move it to a new orbit.  Keeping it where it is has the advantage that I need not add a moon to have appreciable tides- solar tides would be about as strong as Earth's lunar tides.  Not having a moon probably means more perturbation of axial tilt, but that's an issue on scales of tens of thousands of years.  And a Venus year would still be only 224.7 days.

OTOH moving it to a new orbit avoids the need for constant station-keeping on the part of a sunshade.  And, heck, if my planetary engineers can move _Venus_ then they might as well snag Triton as a moon for it.  About 1/3 of Triton's mass could provide volatiles for the terraforming, too (mostly nitrogen and water), leaving a slightly smaller moon to orbit as a satellite.  It would also lengthen the year.  Options include moving Venus into a binary relationship with Earth (which would require ejecting the Moon to avoid the N-body problem), moving it into a binary relationship with Mars, or slipping it into its own orbit midway between Earth and Mars.  (I worry that this would do something terrible to the orbital resonances of these planets, though.)  It cannot be placed on the opposite side of the sun from the Earth, as L3 is unstable.  So are L4 and L5 unless one body is much larger than the other, which would not be the case here- eventually they would collide or one would be ejected.

I'm tending towards the position that if my engineers can spin Venus and give it an axial tilt, then they are probably capable of moving it to a new orbit if they feel like it.  But I'm not sure what _I_ want for my campaign.

Anyway, here are some initial climate maps:

January



The equator and 30-degree parallels are shown.  The north and south map edge are at 57-degrees.  The reddish pseudo-equatorial line is the ITCZ.  Major landmasses are labeled.

July



I'd appreciate if you all could point out glaring errors before I start scribbling a few hundred windsock arrows over the maps.   :Smile: 

I used The Climate Cookbook and PhysicalGeography.net as guides.  

Oddly, I have in some ways recapitulated Earth on these maps- you can see how I have a North and South America, a Eurasia, etc.  Thus I leaned on the latter website a lot.  The wild card is that my Eurasia sits approximately smack on the equator, so if anyone has any ideas about that I'm listening.  Looks like monsoons in Thetis and southwest Ovda?

Also, I can't quite figure out what to do about Alpha and Astkhik.  Their land area is probably too low to have a real continental effect, so I think that I perhaps should do the opposite of what I show here, because they are in the equivalent of my Northern Pacific, which looks like it has a honking big low in January and a mellow high in July.

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## foremost

Again, looks like this was a lot of work, tons
of little islands all over your map. Going to
make for a lot more work when the project
progresses. It's obviously been a few weeks
since you updated, so I hope you are still
going.

My question would be "Why is the heat-band
not directly on the equator?" Maybe this is
as it should be, and I'm  interested to know
why.

Water takes a longer time to heat up or cool
down than land does, and it's also going to carry
some wind currents along with it. The temperature
should also fluctuate throughout the seasons. Does
Venus have seasons?

Anyway, the coastal areas will have more balanced
temperature, thanks to proximity to the water. Inland
areas might be bone-dry and wicked hot as well.

I'm no expert on this, and if you have information
from those websites you mentioned, please share!

Neat project, hope you continue.

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## rgcalsaverini

Great to see a map with such realism! I tend to rush to drawing before settling some necessary things before. I will be following this eagerly!

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## Nathan

Oh ! I really like that !
Impressive !

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## Caenwyr

> Great to see a map with such realism! I tend to rush to drawing before settling some necessary things before. I will be following this eagerly!


Seconded! No patience whatsoever here... though I really should work on that! My sincerest compliments to your perseverence, acrsome!

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## acrosome

Yes, I'm still working on it.  Exactly two days total since my last post, but I warned you all about that.  Careers suck sometimes...

@foremost:  Those aren't "heat bands", they are high- and low-pressure zones.  And the ITCZ is just sort of a line near the equator with equal pressure north and south of it.  I can't explain it in a pithy manner (especially since my own grasp of it is tenuous at best).  If you're interested check out those websites I listed.

Venus terraformed the way that I'm proposing will indeed have seasons.  It's been given more axial tilt, and its spin has been increased.

Speaking of which I wasn't happy with the previous climate maps, so I re-did them making some different assumptions.  I also added winds and currents.  I'm ready to start working out Koppen climate zones soon.

So, yellow are high-pressure zones, blue are low-pressure zones, and the green arrows are prevailing winds:

Here is July:



Here is January:



Here are currents, hot cold and indifferent:



Recall that "hot" and "cold" are _relative_.  I.e. a warm polar current can be colder than a cold equatorial current.

EDIT-- Does anyone have a nice 1000m contour map of the world or of North America, so that I have something to compare to while working out climates?  My Google-Fu is failing me.

EDIT-- I decided that I don't like my first world-spanning map (the file size is simply too big to work with) so I'm currently working on re-doing it as eight regional maps instead.  Luckily, I found a decent set of USGS base maps that includes the poles, so now I can cover the whole planet.  Which is nice, because Ishtar Terra is damned interesting.  I've also been struggling with Koppen climate zones, and I'm getting frustrated.  I need the climate worked out so that I can decide which basins will be endorheic and which will be inland seas or lakes, etc.  But some of these basin seas might be big enough to affect climate.  Grr.  It looks like most of northeast Aphrodite will be a Sahara-equivalent, and there are a few areas with true monsoons in Manatum and in that large bay at the west end of Thetis.

So, more will follow... eventually.

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## acrosome

Here are some initial thoughts on Koppen Climates.  Lines of latitude are in 15-degree increments (this is a Mercator projection that only covers to 57-degrees north and south).

Frankly, a map of _biomes_ like the Hodridge scheme or like this is probably more practical and useful than Koppen climates, but it seems to be traditional to do the Koppen thing.  I'll probably make a biome map later, and the Koppen climates will help me on that.  

There are a lot of landforms that don't really have perfect analogues on Earth, so I made a lot of stuff up.  For example, my huge Himalaya-like mountains are on the equator, so I used the equatorial Andes as a model for them somewhat, and made some SWAGs.  (Actually they're not quite Himalaya-scale; the really tall mountains are in Ishtar.)  A lot of my continents don't have a large north-south mountain range as in the Americas or Himalayan rainshadow like Asia, so I'm not sure how the east-coast and west-coast climates meet in higher latitudes without one.

My large Amazon-like Af rainforest is in eastern Ovda, since that's the only large chunk of tropical land on an east coast right on the equator.  (Equatorial Phoebe is small in comparison.)  I made eastern Atla somewhat similar, though.Generally, since so much of my land is in the tropics there is a LOT of Af, Am, and As.  

So, I guess I'm making a jungle/desert world...

Ulfrun/Atla is a rough analogue of sub-Saharan Africa.  Thus, that enormous BWh desert largely covering Zhibek and Artemis is a Sahara-equivalent.  (There are no large mountain ranges to keep that desert from just cutting all the way across the continent.)  

Eistla will be an Australia-equivalent.  I may change the Umay-ene climate a bit and make it my Madagascar biome.

There is no good Europe-equivalent with an aberrantly high-latitude Cwa climate, unless it's Hathor and western Themis... but I was going to make Themis/Phoebe my South American biome, and make Beta my North American biome.  (Ishtar is probably more like a Canada/Scandinavia bastard child.)

The only _true_ India-like monsoon is that bit in western Thetis; the other Am climates technically meet criteria- like most of the the Amazon- but aren't the intense and brief raging torrent of the Indian Ocean monsoon.

This is all just preliminary, to help me make other decisions such as which low spots to fill as lakes and which to leave as endorheic basins, deciding where the big rivers will be, etc.  Nonetheless, if anyone has any criticisms, fire away.  My eyes were crossing in a lot of spots, so I'm sure that I have some egregious idiocy here, somewhere.

I'm still working on my newer maps that will show the poles as well.  This is important, because there is a lot more of Ishtar down there, and that might end up being an important place.  (I have to think of new names for these landforms...)

I also found GTDR data from the Magellan mission, which is topographical data on Venus.  I thought I'd run it through some manipulations in Wilbur when I get a chance and see what pops out.  Unfortunately, one pixel is 4.6km, so it isn't terribly detailed, and there are a lot of holes and artifacts in the data, but I still think it can help me figure some things out.   

Hmm... I guess that I have a Wilbur question... given data like that can Wilbur for instance double the number of pixels (to 2.3km/px) by extrapolating elevations or somesuch?   (I have yet to download Wilbur- I have to dual-boot some sort of Windows on my laptop, first.)  I wouldn't mind trying to do a nice job with Wilbur on some small area, like Tellus or Eistla, or maybe Beta.  (I understand that Wilbur works best on smaller scales.)

After sangi39 mentioned this inspired study on his Yantas thread I started looking around to see if there was any way I could run my world through the HadCM3L climate model, but I don't think that there is.  Unless, of course, someone here happens to work for the UK Met Office or the Hadley Center...  :Smile: 

A final point:  I was going to name this world *Sypherion*, that being a fictional cognate of _cytherean_, which means "of or regarding the planet Venus."  But then I found Max's map of the city of Yphyrion, and now I don't feel so clever...

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## sangi39

So I've been meaning to reply to this for about 16 days now, but luckily it's all praise, since I don't feel like I know enough to point out any errors lol. Looking at your map and the Koppen climate map for Earth, though, has really made it clear to me that my climate map for Yantas was pretty damn wrong  :Razz:  I mean I don't have tropical rainforests at the poles, but I seem to have been overly simplistic in dealing with certain climate zones  :Razz:

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## acrosome

Oh, I just think that your climate map was a roughing-in, so to speak.  As if you made a map with the suggested latitudes taken very rigidly, and painted in as bands, to use as a guide.  I thought that's a _great_ idea (and probably sufficient for any fantasy mapping needs).  So I stole it  :Smile:  and did something similar, but then looked at the real-world Koppen maps on Wikipedia and did some fleshing out.

I spent a _lot_ of time obsessing over the descriptions on the Wikipedia page.

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## sangi39

> Oh, I just think that your climate map was a roughing-in, so to speak.  As if you made a map with the suggested latitudes taken very rigidly, and painted in as bands, to use as a guide.  I thought that's a _great_ idea (and probably sufficient for any fantasy mapping needs).  So I stole it  and did something similar, but then looked at the real-world Koppen maps on Wikipedia and did some fleshing out.


Huh, how very dare you  :Razz:  I do like the whole idea-sharing thing that goes on here at the Cartographers' Guild  :Smile: 




> I spent a _lot_ of time obsessing over the descriptions on the Wikipedia page.


Yeah, I spend a couple of days on Wikipedia, editing my climate map as I went along, but then I got annoyed and deleted the edits  :Razz:

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## Pixie

That's the problem with keeping the post a WIP when it comes to climate map. You spend so much time looking at it, adjusting and dealing with too many variable (rain, temperature, seasonality, high-low pressures centers, ocean currents, prevailing winds), that you end up unable to 

1. explain the reasoning (if it is your map)
2. understand the reasoning and suggest improvements (if you are the lurker)

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## acrosome

As with, I suspect, most of the larval-stage cartographers who end up here I have discovered Wilbur (all hail Waldronate).  I dug up some Magellan data on Venus topography and fed it through, dealt with some annoying artifacts (thanks Redrobes), and then some more artifacts, etc.  Here are a few preliminary views. 

First, Thetis, Ovda, and Manatum:



The snow line is set at about 14000 feet, by the way.

Next, here's one that shows that southern continent (Ishtar) and the south pole: 



The pole is obvious because it was missing from the Magellan data and I had to clone some in- very inexpertly- and it shows.  It's that first darker ocean basin below the high mountains on the continent.


Since I can use this data to do all sorts of neat stuff with Wilbur, I think I'll use it instead of my hand-traced version from the scanned USGS maps.  I'm still trying to figure out how to export images from Wilbur.  Obviously, I managed to export these, but every time I try to export an equirectangular image- or actually anything _not orthographic_ - it gets truncated at the edges.  This happens even when I set the exported image's size to my map size.  Grr. 

Once I deal with a bunch more little artifacts I'll start exporting it to GIMP, making sea masks, etc.

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## acrosome

Well, I've started playing with this project again, mostly puttering around learning Wilbur.  I also decided to have a bash at Pixie's climate technique to see if my original thoughts jived, so I re-did my sea levels and tried to work out some better and more detailed currents:  



Do you have any critiques of the currents?

One problem I have is that Venus really doesn't have continental shelves.  Also, I'm particularly interested in opinions on three areas:

1. The gyre from Phoebe-Imdr-Zhibek, with the Gulf Stream hitting Imdr.  This is, I suppose, my equivalent of the North Atlantic.  South of that is an equatorial countercurrent, and south still more is a small gyre in the southern part of that sea.  The way I have them interacting seems contrived, though I looked at the 1943 map on the Wikipedia ocean currents page and there seem to be even more dramatic currents crossing the equator in south Asia.  I don't have a terrestrial model for the fact that there are a few small straits that would connect the equatorial gyre with the Beta-Ulfrun gyre.  Thoughts?

2. I based the large southern-hemisphere gyre around Gula and the islands to the west of it on south Asia with all of its islands and straights, so it looks busy but I think it works.  (I didn't try to map every little current in that region, just enough to fun the climate thing.)  Thoughts?

3. The gyres north of Ovda and on either side of Ulfrun- am I doing that right?  Or should they just be 'lobes" off of the polar currents?

And, of course, any other criticisms are not only welcome but appreciated.

Ignore the thumbnail map below- it's old, and I can't seem to figure out how to remove it.

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## ascanius

Your map is very interesting so far.  There are a few areas I would have done differently but this mostly concerns micro currents among the archapelegos.  I however did notic that your polar currents need some work.  For example, the ocean east of Telius, that west coast should be a warm current going south, the black current lines ( >45 degrees) for both poles are the wrong direction and should be traveling west not east.  One thing that helps is to overlay your hot cold pressure systems over the ocean currents to get a better idea of how things line up, ocean currents follow the high low pressure systems of the atmosphere.

I did a quick paint over to show you what I mean.



Hope that didn't confuse you.

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## acrosome

Really?  I was using this and this as sources for polar currents- they show the Antarctic circumpolar currents as being eastward at 60S, though, yes, I had to try to account for the Ishtar and Lada continents being in the way.  (Are you looking at subpolar currents?  These are indeed westward.)  

I see what you mean about the splitting of currents into a warm poleward and cold equatorward branch, especially on that second map I linked- I'll work on that.  I do have something like that around Beta, though I represented it as a very weak southbound current, but you're right I could do a better job around Tellus.  Clearly I shouldn't have that northbound cold current there.  Mostly, though, I have to be sure that I have the direction of the circumpolar currents correct, since that will affect a lot.  Yes, on Earth that splitting occurs in the southern hemisphere and the southern split joins the 60S circumpolar current, but that circumpolar current isn't a westward countercurrent- it is eastward.  If I take southern Earth as my model than the currents you changed arounf Tellus should be more like the currents you added south of Beta- eastward.  Or am I missing something?

Likewise, regarding the minor gyre between Xartanga and Lada- why did you switch the direction?  Are you thinking of Hadley cells?

Or, maybe I should just make both of my poles more like Earth's northern pole, with smaller current "lobes" but no true circumpolar current.  Is that what you mean?  I'm finding the polar currents rather frustrating.  But I want to get this as "good" as I can make it before I proceed further.  (Thank God that since I'm working from real data I don't have to mess around with tectonics.  I might have an apoplexy.)

I'll play around in GIMP when I get home.

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## ascanius

> Really?  I was using this and this as sources for polar currents- they show the Antarctic circumpolar currents as being eastward at 60S, though, yes, I had to try to account for the Ishtar and Lada continents being in the way.  (Are you looking at subpolar currents?  These are indeed westward.)


Sorry, my bad I meant subpolar.  Sorry if that confused you.  You have the ( <45 degree) polar currents right it's the subpolar ( > 45 degrees) currents that need work.




> I see what you mean about the splitting of currents into a warm poleward and cold equatorward branch, especially on that second map I linked- I'll work on that.  I do have something like that around Beta, though I represented it as a very weak southbound current, but you're right I could do a better job around Tellus.  Clearly I shouldn't have that northbound cold current there.  Mostly, though, I have to be sure that I have the direction of the circumpolar currents correct, since that will affect a lot.  Yes, on Earth that splitting occurs in the southern hemisphere and the southern split joins the 60S circumpolar current, but that circumpolar current isn't a westward countercurrent- it is eastward.  If I take southern Earth as my model than the currents you changed arounf Tellus should be more like the currents you added south of Beta- eastward.  Or am I missing something?


Also look at your source image, the really detailed one (2nd one)  it only shows up to 60 degrees and doesn't show the full 90 degrees lat, I think this is why your getting a little confused.  Your not getting the full picture.  The current does go eastwards but it's around the 45 parallel.  Also note the antartic subpolar, it is more of what I was getting at.




> Likewise, regarding the minor gyre between Xartanga and Lada- why did you switch the direction?  Are you thinking of Hadley cells?


As to why I switched the directions, if you look at the two sources your using you will see that around 45 degrees latatude the currents travel eatward then the current splits at a landform/ice with warm moving north and cold going south.  There is a long scientific reason why this happens but suffice it to say it's due to the rotation of the planet.  The currents you are mapping are the surface currents wich are created by the prevailing winds caused by Hadley cells.  The basic idea is closed loops, with the east/west flowing currents traveling until they are split by land then warm goes towards poles and cold towards equator.  

With Xartanga and Lada the polar current travels eastward until it encounters land (the southern islands of Lada for simplicities sake) at this point the current splits with warm going towards the pole and cold going towards the equator closing the loops.  That split doesn't occure prior encountering an obstical (land).  {Not entirely true what you see in real life is a warm current drift north with the greatest concentration along the costs (warm current only)  the cold current doesn't doe the same thing.}--> ignore this if it confuses you it's not important.




> Or, maybe I should just make both of my poles more like Earth's northern pole, with smaller current "lobes" but no true circumpolar current.  Is that what you mean?  I'm finding the polar currents rather frustrating.  But I want to get this as "good" as I can make it before I proceed further.  (Thank God that since I'm working from real data I don't have to mess around with tectonics.  I might have an apoplexy.)


check these out they might help you out .  http://www.divediscover.whoi.edu/arc...rculation.html
http://beyondpenguins.ehe.osu.edu/fi...c_currents.jpg
http://polardiscovery.whoi.edu/antar...ulation-en.jpg


good luck

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## acrosome

> Sorry, my bad I meant subpolar.  Sorry if that confused you.  You have the ( <45 degree) polar currents right it's the subpolar ( > 45 degrees) currents that need work.
> 
> Also look at your source image, the really detailed one (2nd one)  it only shows up to 60 degrees and doesn't show the full 90 degrees lat, I think this is why your getting a little confused.  Your not getting the full picture.  The current does go eastwards but it's around the 45 parallel.  Also note the antartic subpolar, it is more of what I was getting at.


Well, that more detailed second map I linked show a broad eastward circumpolar current from about 45S to >60S, so that's what I tried to emulate.  The first (more simple) map also shows it at 60S.  I figured that the westward subpolar currents would be at >60S, and didn't really bother to chart them.  So you're basically saying to present the circumpolar current as being at a lower latitude than 60, right?

What messes me up, as I mentioned, is that I have landmasses at 60S in both the north and south and I'm not sure what effect that will have.  Thus my question about if I should just model those after the far northern Atlantic, or the small gyre through the Bering Sea, etc. on the more detailed map.




> As to why I switched the directions, if you look at the two sources your using you will see that around 45 degrees latatude the currents travel eatward then the current splits at a landform/ice with warm moving north and cold going south.  There is a long scientific reason why this happens but suffice it to say it's due to the rotation of the planet.  The currents you are mapping are the surface currents wich are created by the prevailing winds caused by Hadley cells.  The basic idea is closed loops, with the east/west flowing currents traveling until they are split by land then warm goes towards poles and cold towards equator.


Ah, never mind- I see it now on that detailed map.  I had a chart reading failure there for some reason.  I'll have to fix that. 




> With Xartanga and Lada the polar current travels eastward until it encounters land (the southern islands of Lada for simplicities sake) at this point the current splits with warm going towards the pole and cold going towards the equator closing the loops.  That split doesn't occure prior encountering an obstical (land).  {Not entirely true what you see in real life is a warm current drift north with the greatest concentration along the costs (warm current only)  the cold current doesn't doe the same thing.}--> ignore this if it confuses you it's not important.


I went to pretty extraordinary lengths to close loops, actually.  (Note the numbers next to the currents.)  But, as I said above, I have some reworking to do...

I'm checking your links, now.

EDIT:

That first one is a _damned_ cool chart of arctic currents.

But that third link of yours is what I'm talking about- the circumpolar current looks like it runs as high as >60S for about 3/4 of the way around Antarctica.  Still, it clearly does _not_ for 1/4.  So I can tweak that, too. 

Looking at my poles in orthographic projection on GProjector I'm starting to think that I need to model both of them on the Arctic rather than the Antarctic. 

I'm going to go cry into my pillow for a bit, and once I've recovered my composure I'll start over.  It may be a while.

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## talisid

First off, I want to say that your project - both the idea and execution - are awesome and inspiring.

Second, since my knowledge is lacking, instead of offering advice, I offer a resource that you are (I assume) unlikely to encounter online, an inset from the 1966 National Geographic Atlas of the World. I'm like 99.5% sure this counts as fair use since it is far less than 5% of the book, is being used for "educational" purposes, and would have to have had its copyright extended to not be in public domain by now. That said, if I should remove it let me know.

It shows warm and cold currents, along with prevailing wind direction. I can take better photos or maybe get an actual scan of it if you want, and I hope that it will at best help out and at worst not ruin anything!

Keep up the awesome work.

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## ascanius

> I went to pretty extraordinary lengths to close loops, actually.  (Note the numbers next to the currents.)  But, as I said above, I have some reworking to do...
> 
> I'm checking your links, now.
> 
> EDIT:
> 
> That first one is a _damned_ cool chart of arctic currents.
> 
> But that third link of yours is what I'm talking about- the circumpolar current looks like it runs as high as >60S for about 3/4 of the way around Antarctica.  Still, it clearly does _not_ for 1/4.  So I can tweak that, too. 
> ...


Lol.. You got this. besides all you need to change is the subpolar currents to the opposite direction, it's an easy fix.  I don't think you need to worry so much about the subpolar currents what you have works well once you change the direction.   keep it simple first then add complexity.  One thing could you add the lines of latatude.  Keep up the good work.  I'm very interested to see how you do the atmospheric pressure systems and climate, though I don't envy you with all the microclimates your going to have to do.

Also.  I think the reason why the antartic map show the current going east until 60 is because there is nothing (landform) to break up the currents flow.  The currents don't exactly travel in a east west line but drift polar if they are warm and equatorial if the cold.  With antartica the currents more or less run parallel with the continent.  However if you look at Talisid's map below you will see that very close to coast of antartica the current is westward.  Your map has enough subpolar landmass to change things more towards what I showed you in the paintover.




> First off, I want to say that your project - both the idea and execution - are awesome and inspiring.
> 
> Second, since my knowledge is lacking, instead of offering advice, I offer a resource that you are (I assume) unlikely to encounter online, an inset from the 1966 National Geographic Atlas of the World. I'm like 99.5% sure this counts as fair use since it is far less than 5% of the book, is being used for "educational" purposes, and would have to have had its copyright extended to not be in public domain by now. That said, if I should remove it let me know.
> 
> It shows warm and cold currents, along with prevailing wind direction. I can take better photos or maybe get an actual scan of it if you want, and I hope that it will at best help out and at worst not ruin anything!
> 
> Keep up the awesome work.


Nice map.  I'm pretty sure that it counts as fair use.

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## acrosome

> Lol.. You got this. besides all you need to change is the subpolar currents to the opposite direction, it's an easy fix.


Lol... I never drew subpolar currents.  That's what I'm saying.  The currents near the poles for which that you switched the direction were my 60-degree circumpolar currents, which it looks like should indeed be going east as I had them.  Circumpolar.  I think we got messed up on terminology. (See that first map I posted- that's the terminology I'm using.)  You seem to be saying that I should make my circumpolar current lower than 60 degrees, which I'll buy- I'm working on new currents, basically starting from scratch.




> However if you look at Talisid's map below you will see that very close to coast of antartica the current is westward.


Yes.  And those are subpolar currents, not circumpolar currents.  I agree- and knew all along- that subpolar currents are westward.  You seem to want me to draw maps without circumpolar currents, regarding which:




> Your map has enough subpolar landmass to change things more towards what I showed you in the paintover.


The landmasses near but not on the poles (unlike Antarctica which _is_ on the pole) are what I was talking about when I mentioned that maybe I should be making my polar currents look more like the Arctic than the Antarctic.  The Earth's crowded northern pole prohibits a circumpolar current since there's land sitting on 60N, and instead you get those odd lobes off of the northern gyres, as in those currents near Alaska and Scandinavia on that second map of mine.  Looking at my Cytherian poles in orthographic projection on GProjector I suspect that my southern pole at the very least probably has very Arctic-like currents- similar to those maps of Arctic currents that you posted.  Here's the south pole (with my old currents- ignore them):



Another thing this view shows is (I think) your point about my eastward/clockwise circumpolar current.  I have it at too high a latitude to allow room to squeeze the westward subpolar currents in.

So now I'm probably just down to puzzling out the northern polar currents.  For completeness' sake, here's the north pole:



When I next post currents I think you'll see what I mean.  I might just post the major currents first to see what you think of them.  But I got sidetracked filling basins in Wilbur for a while...

----------


## johnvanvliet

mind you the currents will be opposite of the earths  
venus rotates backwards and very SLOW 

a day is longer than the year  
so not much in the way of Coriolis effect  from the rotation

a bit od an oldish quote



> I also found GTDR data from the Magellan mission, which is topographical data on Venus. I thought I'd run it through some manipulations in Wilbur when I get a chance and see what pops out. Unfortunately, one pixel is 4.6km, so it isn't terribly detailed, and there are a lot of holes and artifacts in the data, but I still think it can help me figure some things out.
> 
> Hmm... I guess that I have a Wilbur question... given data like that can Wilbur for instance double the number of pixels (to 2.3km/px) by extrapolating elevations or somesuch? (I have yet to download Wilbur- I have to dual-boot some sort of Windows on my laptop, first.) I wouldn't mind trying to do a nice job with Wilbur on some small area, like Tellus or Eistla, or maybe Beta. (I understand that Wilbur works best on smaller scales.)



if you still need a DEM
here is one i made that is 16384x8192 px 
*  the below link is no longer working 
those that need it have it*  

https://drive.google.com/file/d/0B6Z...ew?usp=sharing

from 
http://pds-geosciences.wustl.edu/mgn.../mg_3002/gtdr/
holes filed and upscaled using a SFS algorithm on the radar mird FULL data 
http://pds-geosciences.wustl.edu/mgn...r-full-res-v1/

----------


## acrosome

> mind you the currents will be opposite of the earths  
> venus rotates backwards and very SLOW 
> 
> a day is longer than the year  
> so not much in the way of Coriolis effect  from the rotation


If you look closely, my maps are rotated 180 degrees.  I've flipped them so that "east" is the direction that the sun rises.  Yes, this swaps the north and south poles, but it also means that I can more directly model currents and winds on Earth.  Or to put it another way, the way that I have these maps oriented means that I can use Geoff's Climate Cookbook and Pixie's method as-is.  I discuss this briefly in the second or third post.

Likewise, for terraformation purposes the rotation has been sped up to a 24 hour day and a bit of axial tilt added.  (This is both to simplify worldbuilding and also to try to disguise the identity of the planet from RPG players- something that is hard with Mars.)  Speeding up rotation will deform the planet into a more oblate spheroid, adding about 40 miles of equatorial circumference, which I'll assume is new rifting.  I'll add the rifts where I need them to drain basins and such.  This all also gives me an excuse to restart vulcanism in spots.  (Though no one really knows if Venus is still volcanically active or not.  It doesn't work like Earth- there are no tectonic plates.  One theory is just massive resurfacing via volcanic events every few million years.)  I haven't decided if Venus has been moved out to a wider orbit, but probably.

That's a DEM of Venus?  Well, if it's better than mine (and it almost has to be) I'll definitely be checking it out when I get home.  That's huge, though- it might break my MacBook!  Thanks!  Though on the downside that probably means that I'm back to the drawing board again...  My main concern is all the damned streak artifacts and holes in the Magellan data.  Did you fix those?  That's what consumed most of my time- fixing those and cloning data into the holes (poorly- I'm no artist).

----------


## acrosome

Wow.  Your DEM is much better than mine.  I can actually see the texture of ridgelines in the mountain ranges (which I knew were there from looking at USGS radar maps of the planet).  And it lacks all of the holes and artifacts that I have in mine.

But your data generate much different coastlines than mine when I play with it in Wilbur!  Is this Magellan data, or is it from some other source?  Because if it is Magellan I would expect it to match my coastlines.

Nonetheless, this is clearly better than mine, which means starting over again from scratch...

Thanks?   :Smile: 




Other old tries:

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## johnvanvliet

> Is this Magellan data, or is it from some other source? Because if it is Magellan I would expect it to match my coastlines.


it is 
cleanning up the data from here
http://pds-geosciences.wustl.edu/mgn...02/gtdr/sinus/

changed it a bit  that sinusoidal projection map is VERY noisy 

then it was merged with a data set derived from the RADAR reflectance  map using a Shape from shade program to make a" high frequency " layer for the height data 

then joined  the high freq and low freq information into one image
this also means it is no longer 100% scientific accurate  


the map i posted on my G-drive is using this mapping group ( i use ISIS3  gis ) 


```

 Group = Mapping
    ProjectionName     = SimpleCylindrical
    CenterLongitude    = 0.0 <degrees>
    TargetName         = Venus
    EquatorialRadius   = 1737400.0 <meters>
    PolarRadius        = 1737400.0 <meters>
    LatitudeType       = Planetocentric
    LongitudeDirection = PositiveEast
    LongitudeDomain    = 180 <degrees>
    MinimumLatitude    = -90.0 <degrees>
    MaximumLatitude    = 90.0 <degrees>
    MinimumLongitude   = -180.0 <degrees>
    MaximumLongitude   = 180.0 <degrees>
   # PixelResolution    = 0.0 <meters/pixel>
    Scale              = 45.5111111111 <pixels/degree>
  End_Group
```

----------


## acrosome

> it is 
> cleanning up the data from here
> http://pds-geosciences.wustl.edu/mgn...02/gtdr/sinus/


Ah, yes, so it's mostly Magellan data.

Well, it's an f-ing Thing Of Beauty.





> changed it a bit  that sinusoidal projection map is VERY noisy


Truth.




> then it was merged with a data set derived from the RADAR reflectance  map using a Shape from shade program to make a" high frequency " layer for the height data 
> 
> then joined  the high freq and low freq information into one image
> this also means it is no longer 100% scientific accurate


I had come to suspect that it used a different geoid or something.  So if you used radar reflectance then all the surfaces that are radar reflective (viz. rough/young) will look a bit higher than reality in this DEM?  Or am I misunderstanding?  




> the map i posted on my G-drive is using this mapping group ( i use ISIS3 gis ) 
> 
> Code: ...(snip)


Now you're getting a bit beyond me.  Actually, for the most part, more than a bit.  So you mapped it as a perfect sphere?  (Actually, Venus is pretty damned close to a sphere, isn't it?)

So, granted that the nearly Godlike terraforming that I'm invoking here will reshape the world considerably, I'm mostly concerned with my sea level being appropriate.  Given your manipulation of this data, if I set a given elevation in your DEM to sea level (in Wilbur e.g.) would that be close to accurate re: water finding it's level, or would it be totally off?

Here's a decent sea level:

----------


## johnvanvliet

so you are going with NORTH on the bottom of the map 

as to your "sealevel" and mine 

the image "16kVenusDEM.tiff" the mean average is 8065 

however  if you add the value "6039999" to the pixels you will get the  Radius in Meters   but i only scaled it to the min/max values

----------


## acrosome

> so you are going with NORTH on the bottom of the map


Yes, so that the sun rises in the east.  Mind you, I'm still going to call the top of the map "north" and the bottom "south."  As I mentioned before, this is to keep to familiar conventions for any notional RPG players that may eventually have characters inhabiting this world.




> as to your "sealevel" and mine


Oh, so you're doing the same project?  I'd be interested to see what you've got.  I'm planning to fill a lot of those more dramatic inland depressions as lakes (i't a bit of a project to figure out their elevations) but I'm going to fill some of the more shallow ones.  And a few will just be depressions in desert areas, though it looks like when I use your data that the desert in Artemis won't be quite as huge.




> the image "16kVenusDEM.tiff" the mean average is 8065 
> 
> however  if you add the value "6039999" to the pixels you will get the  Radius in Meters   but i only scaled it to the min/max values


Yes, I think I grok that.

I did elevations the easy way: in Wilbur I did _Filter>Mathematical>Span_ and set it from -19250 to +25683.  This sets elevations in feet with the sea level as in my map above.  (I'm generally a metric guy, but from all of the North American hiking I do I'm used to thinking in feet for elevations.)  This is derived by the lowest point (1.8 miles below the mean radius) and the highest point (6.71 miles above the mean radius).

----------


## acrosome

Still slowly working.  Here's some (very minimalist) labeling:

----------


## jkat718

Looks good, acr! I particularly like the coloring, both for the labels and for the terrain itself.

----------


## acrosome

> Looks good, acr! I particularly like the coloring, both for the labels and for the terrain itself.


The terrain is all Wilbur at this point, I'll pass the praise on to Waldronate.  Well, except for the below-sea-level basins, which I have temporarily filled with that psychedelic green tint.  I'm no artist.  This is more an exercise in worldbuilding for me.  As I slowly figure out GIMP I'll keep trying to makle it prettier, but that's after I've done the worlbuilding.  I need know where it rains, for instance, before I can tint the vegetation, decide if a basin is a lake or a salt flat, etc.

Regarding the labels- I finally sat down and figured out how to text-to-path in GIMP, so I'm playing around with it a bit.  For that matter, I think that I finally understand layer masks.  Woop!

----------


## acrosome

Y'know, for a forum about *maps* the 4MB upload restriction is kind of draconian...

So, working with johnvanvliet's (much better) data, here are some ideas for currents:



Fire away- critiques welcome.  

Ascanius- I tried to make the wide 45-60 degree eastward current discrete from the westward subpolar current that we were getting wrapped up about.  I need to better define where the cold currents drop out of the poles.

My oceans are broken up much more than on Earth, with many islands, so there there are a lot of meandering warm currents that I modeled on the Southeast Asian currents.

With the new data (and thus new coastlines) there is no longer a Gulf Stream hitting Imdr.  Instead, it looks like northern Themis has one.

----------


## ascanius

Looks good, I like this version a lot more the landmass don't have those weird extreme rifts/ravines any more.  The colors and everything else also look a lot clearner.  As for currents everything looks good but the Russalka gulf and Himenoa sea would probably have equatorial currents like those in the center of the map.

I'm currious how high are the mountains in Ovda and Ishtar.  I could see Ishtar being covered in frozen carbon dioxide at the heigher elevations.  I think it would be cool to see some of the mountain ranges from the planet surface.

----------


## acrosome

The Ovda and Thetis mountains top out at ~18,000 feet and the Maxwell Montes in Ishtar top out at ~25,500 feet with this sea level.  So the former are Alp equivalents, and the later are Himalaya equivalents.

The rifts and ravines are still there- I just colored them in bright green until I can work out climate and decide which are going to be dry basins and which will be lakes or seas, etc.  There will be a particularly large one in western Aphrodite.  But I've been experimenting and I'll probably fill all of the lesser basins. I've gotten facile enough with Wilbur that I'm geeting reasonably good looking results after some basin fills and a few gentle erosion cycles.

But, damn, you struck right to a couple of areas that gave me heartburn- Russalka and Hinemoa.  In short, I just reviewed that 1943 map on Wikipedia and I see that you are right.  I'll tweak those.  Hinemoa is a bit of a tougher nut, though- there is no Earth equivalent for an enclosed sea like that on the equator.  Hinemoa is going to be weird, not least because my research reveals that (small-m) mediterranean seas' currents are often driven more by differences in salinity than by wind.  So I'm not going to feel too put out if it doesn't make total sense _viz._ winds.

What do you think of the Undine Sea connecting Hinemoa to Guinevere?  I'm having trouble wrapping my head around that one.

I've also tweaked a few minor currents in the Lada Sea since I posted that last map, and added a few more minor currents.  Working out the high and low pressure zones and winds is also odd, since my largest continent is right on the equator and there is no equivalent of Siberia to make a nice, strong low.  Ishtar probably acts more like Antarctica than like Siberia.

EDIT---

How does this look:



Doing the initial work on weather, here is my great conundrum: the ITCZ.  I have to decide whether or not it flops back and forth to the north and south of the equatorial mountains in Aphrodite, or if it stays to one side.  Any thoughts?  If it ever runs north of them that'll have dramatic effects mitigating _against_ a huge desert in the Artemis Chasma region as I had on my earlier climate map.  I have to admit I kind of liked the megadesert, but having the ITCZ flop around that much would make for some interesting weather.  Maybe I could waffle and say something like "The ITCZ flopping north of the mountains happen about once a decade, and has profound effects when it does" or somesuch.

----------


## acrosome

I've been fighting a lot with the high and low pressure zones.  I tried a new technique:

 

Here are the winds:

 

Inspiration found here.

Criticisms?

Frankly, none of the landmasses at about 30 degrees are very large, so they shouldn't have very strong summer lows- certainly nothing like the monstrous Siberian low.  So I think their effect will be small.  To show this weakness it might be best to represent them as just _not high_.  This is a bummer, because I wanted a true monsoon _somewhere_.  Maybe in that gulf between Thetis and Ovda, on the southern shore of Aphrodite?  It would be an odd April/May monsoon...

I also think that with Pixie's method you have to think of the ITCZ and the polar fronts as standing low-pressure zones.  Thus, think like both poles are _high_ pressure, with winds moving toward the polar front.  I'll change that.

----------


## ascanius

Hey.  I think you figured out the currents.

I don't understand what your doing with the subtropical high pressure systems, I think your using two colors to show strength right?

looking at your map I can see venus would be a great vacation spot with a lot of tropics along the ocean.  Too bad it's extreamly hostile in real life.

Cant wait to see how you do with the climates.

Edit:   meant to delete that sentence about Beta.

----------


## acrosome

Regarding colors: yes, darker shades of yellow for higher highs, darker shades of green for lower lows, etc.  (And, yes, I got the poles wrong- they should be highs.  When I get home I'll post the updated maps.)

You say that Beta would have a low in both seasons?  How do you figure?  Geoff's cookbook (and other sources) mention continental _highs_ in winter.  Did I miss something subtle?

And, yes, it's like someone shoved Asia southward until it sits on the equator...

----------


## ascanius

> You say that Beta would have a low in both seasons?  How do you figure?  Geoff's cookbook (and other sources) mention continental _highs_ in winter.  Did I miss something subtle?.


Ignore that portion.  I meant to delete it, I was thinking of something else.

----------


## su_liam

We need a name for that little inland sea cutting into Aphrodite Terra and communicating with the Zhibek Sea and Russalka Gulf. Feels like a good place for a Europe-ish upstart civilization! Not to say the Venus map doesn't provide lots of such opportunities. Is the equatorial region going to be shaded and cooler? Nice bit of alien color that would be!

This map is getting sexy. Is there going to be a political map?

----------


## acrosome

> We need a name for that little inland sea cutting into Aphrodite Terra and communicating with the Zhibek Sea and Russalka Gulf. Feels like a good place for a Europe-ish upstart civilization! Not to say the Venus map doesn't provide lots of such opportunities. Is the equatorial region going to be shaded and cooler? Nice bit of alien color that would be!
> 
> This map is getting sexy. Is there going to be a political map?


The sea just north of the A in Aphrodite is a tough one- it isn't a named planitia as far as I can tell.  The USGS geologic map of that region lists the surface as "Ceres, Bona, and Miralaidji coronae flow material."  So I'm still thinking about that one, but it'll probably be named after whichever one of those seems most appropriate, once I figure that out.  

The straight connecting that problematic area to Russalka is Dali Chasma, thus presumably the _Dali Straight_.  The sea and straight running north to Zhibek is mostly the collapsed part of Atahensik Corona, thus possibly the _Atahensik Sea_.  I'll add these for my next posted map, but the text will be quite small.

And, yes, one of the reasons that I settled on this particular sea level is how "interesting" it made this area.  But I'm not going to have shades- I'm probably going to move Venus into a wider orbit instead.  This is _probably_ going to be a fusion area of the pseudo-African and pseudo-Asian cultures.

A political map is a long way off.  I'm going to start with rough areas assigned to certain cultures and try to model (i.e. make up) migrations and histories running to the "present."

----------


## su_liam

Yeah. To do the politics right, you really need to get the physical attributes _down_. The OCD way I try to do it, that'll take forever.

At least with a RL planet, you have a plausible topography ready-made. And a nice set of names!

Frankly, if I was doing it, I'd prefer the shadow ring. If the Solar day on Venus wasn't so _very_ inconveniently long, I'd divide the day into several ~24 hour segments and a long night. No reflectors lighting up the night 'cause we _don't want_ to increase insolation! But this is your project, and the night is so long, it would play hob-holy-hell with any Earth-derived ecology anyway. Bugger all!

I'm looking forward to seeing where you go with this.

----------


## acrosome

Hey, All.  I've started playing around with this project again.  I was motivated by Azelor's climate method.  I've thought about this project a lot, though.  

I have decided not to use jonvanvliet's data, which is a shame because it is both beautiful and highly detailed.  But it is not really elevation data- it's a combination of elevation and MIDR.  MIDR was Magellan's maps that measured radar reflectivity, which is a measure of surface roughness- so very rough lava fields were bright, and smooth flows were dark.  Averaging this with elevation data made rough areas seem artificially high, and smooth areas seem artificially low.

So I found the best Magellan elevation data that I could- which is not really very good, actually.  The highest resolution available is 4.6km/pixel (which contrasts with _tens of meters per pixel_ for some MIDR data).  Also, there are a lot of missing areas and artifacts.  Luckily, a large majority of artifacts were in low regions that would eventually be seas, so though it was tedious I was eventually able to fix it.

Here is the final Wilbur texture:



The snow line there is set at around 10,000 feet, and green changes to brown at about 5,000 feet.  On behalf of my countrymen I apologize for the use of the archaic units of measure.  But frankly, weird units sort of work better for fantasy, anyway.  Perhaps I'll annotate my next map in stades.

Note that these images have been shrunk, so they are not 4.6km/px.  My original is 8192 x 4096 px.  Also of note- that large continent on the equator is split into two land masses by that knot of channels near it's middle.  (This is one reason that I chose to go with this sea level.)  This is where African and Asian biomes will meet. 

Here is a topo map using Azelor's method and colors:



It's actually kind of handy that so much of that Asian continent is so high in elevation, as this will mitigate being on the equator somewhat.  Presumably most of that lower, northern part of it around the crescent-shaped Artemis Chasma will be desert, since it is in the correct latitudes.

Recall that I have rotated these maps by 180 degrees from the orientation used by the astronomers.  This is to keep the convention that east is "the direction where the sun rises" and then the other cardinal directions follow from there.  Also, it helps to hide the identity of the world from RPG players who otherwise might recognize it (which is an even harder problem on Mars).

Here's that map again in Winkel Tripel:



Next will be currents (again), winds (again), and pressure zones (again).  I have made a layer from Wilbur with some large lakes (there are a _lot_ of deep chiasma on Venus) but I need a general idea of climate so that I know which are lakes and which are dry depressions... and then I'll have to re-do the climates to take into account the lake effect.  Again.

Sigh.

I find myself repeating my work a lot...

----------


## waldronate

I had always considered Venus to be an odd choice for terraforming due to its unfortunate dry geology. Removing enough atmosphere, introducing enough water, and spinning up that sucker to get human-desirable characteristics will wreak all sorts of havoc as those minerals start to hydrate and that rigid crust shatters from the flexing. Not a nice place to be for a very long time after the initial burst of change...

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## bandersnatch

Rad project, subscribed.  :Smile:

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## acrosome

> I had always considered Venus to be an odd choice for terraforming due to its unfortunate dry geology. Removing enough atmosphere, introducing enough water, and spinning up that sucker to get human-desirable characteristics will wreak all sorts of havoc as those minerals start to hydrate and that rigid crust shatters from the flexing. Not a nice place to be for a very long time after the initial burst of change...





> I had always considered Venus to be an odd choice for terraforming due to its unfortunate dry geology. Removing enough atmosphere, introducing enough water, and spinning up that sucker to get human-desirable characteristics will wreak all sorts of havoc as those minerals start to hydrate and that rigid crust shatters from the flexing. Not a nice place to be for a very long time after the initial burst of change...


Not to mention that my backstory involves energies that damned near approach Kardishev II, so I could probably do whatever I liked with the surface, but kewlness dictates that I use the real topography.  I like round numbers, so I spun the planet up to a 24-hour day, and nudged the orbit out to a 240-day year, meaning 20-day "months". At those energies the problem isn't "can we do it?"  It's "can we do it without vaporizing the planet?" because even with 99% efficiency the waste heat can easily exceed the gravitational binding energy of Venus.  So they had to move it _slowly_.  Placing a soletta sunshade was _trivial_ after that.

So, in practice, I stopped feeling bad about the low resolution of my heightmap.   :Smile: 

The _geology_ of Venus is actually kind of fascinating.  Among other things a lot of metals that you wouldn't expect exist on Venus in elemental form in chondrules in the rock, like _aluminum_ and _titanium_.  So my low-tech pseudo-fantasy is going to have aluminum.  Which means having incredibly corrosion-resistant _aluminum bronzes_.  (Titanium, unfortunately, is simply too difficult to work with and really only exists in small concentrations mixed with aluminum or calcium, anyway.)  These various metal chondrules might be found in hydraulic deposits left from the flood stage of the terraformation project.  Yes, part of it would oxidize, but a lot wouldn't.

Happily, Venus is abundant with clay minerals, so building soils isn't as difficult as it might be.

One scheme to get rid of some of that hellish CO2 atmosphere involves precipitating the carbon into carbonates using calcium, magnesium, and potassium.  Then the the calcium carbonate can be used as fill in some basins, leading to pseudo-limestone on a world otherwise nearly devoid of sedimentary rock (there are otherwise a few aeolian formations that qualify).  Of course to do this you need excess oxygen but, as I said, Kardishev II.

The crust shattering is actually kind of helpful in one way.  An astrophysicist figured that spinning up to a 24-hour day would flatten the world into a more oblate spheroid and add about 40 miles of equatorial circumference.  Presumably this will manifest as new rifting, which I can use as justification to drain or connect to the sea some basins that otherwise would be inconveniently large lakes.

Sometimes sticking to real science leads to neat inspirations for a setting.




> Rad project, subscribed.


Thank you.  It has at least been fascinating learning about a planet in which I would otherwise not be very interested.  I'm actually more of a Mars fanboi, but Mars's gravity and people's familiarity with it were undesirable.

----------


## waldronate

It's been a few years since I looked at Venus stuff, so bear with me a little. The fun part of dry rocks is that they are fantastically strong and melt at higher temperatures. Adding water will cause their volume to increase a bit, their strength to decrease dramatically, and they will melt much more easily. Venusian mountains look odd to us here on Earth because they are made out of things that we don't have: dry rocks. Those mountains would be unstable geologically and very chemically reactive at first. Nothing that can't be overcome with some work, but not terribly welcoming in the short term.

If you subscribe to the cataclysmic resurfacing idea for Venus to explain its uniform crater distribution and the apparent single age of its surface, then spinning it up and flexing it causes the entire surface to shatter and sink into the mantle over a few tens of millions of years. That's not a problem in the short term, but it would have the potential for stories about whole countries that just tipped up and disappeared into a great pool of magma.

Blocking the sun and gently lowering an ocean or two's worth of water ice comets onto it would certainly give an exciting result (dropping the comets at normal orbital speeds to spin up the planet would mess with the topography). It would be downright fizzy on that planet for while. Kickstarting a carbon cycle and water cycle at the same time in a massively oxidizing environment would be pretty fun!

----------


## acrosome

> If you subscribe to the cataclysmic resurfacing idea for Venus to explain its uniform crater distribution and the apparent single age of its surface, then spinning it up and flexing it causes the entire surface to shatter and sink into the mantle over a few tens of millions of years. That's not a problem in the short term, but it would have the potential for stories about whole countries that just tipped up and disappeared into a great pool of magma.


The cataclysmic model seems well-supported, but I'm not sure about "shatter and sink into the mantle."  First, I'm re-starting volcanism.  Also, spinning Venus up would presumably change deep convection quite dramatically.  This all might actually help preserve the current crust since the cataclysmic model- which relies upon uncontrolled heat buildup caused by a lack of convection or venting- might no longer apply.  But, yes, things certainly would be rather sporty on the surface for a while.

Or, at least there is enough uncertainty on the issue for me to ignore it for the time being.   :Smile: 

And you could argue that the Earth has issues on the tens of millions of years scale as well, what with our plate tectonics and all.  Eventually Bavaria is going to subduct under the Alps and get recycled...

----------


## Azélor

Isn't there a strata in Venus atmosphere where humans could survive if we managed to build floating cities? (without any terraforming)

----------


## acrosome

> Isn't there a strata in Venus atmosphere where humans could survive if we managed to build floating cities? (without any terraforming)


Yes, using aerostats.  It turns out that a breathable mix of nitrogen/oxygen would be buoyant in the Venusian atmosphere.  You could just build a city inside a gigantic gasbag and float it, and  manage the buoyancy to a stratum on Venus that is of reasonable temperature and pressure, which in this case would be ~50km altitude (which happens to be about 1 bar and 0C-50C).  The atmosphere still wouldn't be breathable of course, but just being at 1 bar and a reasonable temperature makes the engineering involved _much_ easier.

Actually, it turns out that something similar is true of Jupiter and Saturn...

I fixed some artifacts that probably nobody but me would ever notice, and added some minimal labels:

----------


## acrosome

OK, here's my preliminary shot at currents and pressure systems, for you all to rip apart!   :Smile: 

But seriously, I'm open to any criticism at all.  I'm feeling kind of weak on these subjects.

First, currents:



This was actually rather annoying.  I don't have two large land masses running north/south to break the planet up in neat ways, like Earth.  I'm not sure how all of those islands will affect things, but I tried to model it roughly on Southeast Asia, Malaysia, Borneo, etc.  In particular, the way that currents might run between Pheobe and Artemis confounds me.  (And it doesn't help that it's at the map edge.)

Also, I think that the way the currents generally run through those many channels that break the large equatorial continent in two is going to be _very_ important for climate mapping.  Any ideas?

I modeled that odd gyre south of Beta on the one in the far north Atlantic.

Here are the pressure systems and winds.  Yellow is low pressure, green is high pressure:

January:



July:



Once you have beaten me up enough about these (I'm looking at _you_, Azelor) I'll start on humidity, temperature, etc.  In particular, do you think that Ishtar (the large southern continent) is large enough to develop that big summer low?

Climate is going to be a lot of fun, with that huge continent with high mountains sitting right on the equator.

----------


## jbgibson

While you don’t have quite the Continental spread that earth does, it might simplify your currents (and generate other interesting effects) if you sketch in Continental shelves connecting many of the islands.  If ocean is shallow enough it can plausibly steer currents almost as well as coastlines :-).  Even if not extremely shallow, if a basin is cut off enough to discourage flow-through currents to drain away heat, you could get some powerful heat-engine storm drivers - see the Gulf if Mexico...

A ‘nice’ (well... interesting - maybe not so nice for the residents) effect of a bunch of warm shallow sea is the enhanced potential for cyclones/hurricanes.

----------


## acrosome

Thank you.

Hmmm.  I'll have to look for some potential storm generators.  That sounds interesting.  Any ideas on what sort of shallow depths are needed?  Any examples from Earth?  The Caribbean is about as deep in the basins as the Atlantic, so how does that work?   

But Venus doesn't have continental shelves per se.  It doesn't work the way Earth does.  That's why the mountains don't look "right", either.  It's surface is volcanic, and relief depends upon where the lava has flowed and where the rifts have formed.  The current theory is that the whole planet undergoes massive destructive resurfacing (i.e. it melts and/or drops into the mantle for recycling) every few hundred million years due to heat buildup from a lack of decent convection.

Here's one map showing some shallows (a repeat from the previous page):



I forget how shallow water had to be to be light blue- I want to say 500 feet.  I can produce something again when I get home.  What would be a good cut-off for ocean depths to affect currents?  The Wikipedia page implies that defining a shelf is more a matter of slope than depth.  Knowing what I do about Venus, most of the oceans will have enough slope almost instantly offshore, so this map might actually be decent for this purpose.  Or I could have Wilbur spit out a slope map, but I might have to play around with that quite a bit to get something useful.

Some of those currents south of the equatorial continent (Aphrodite) might get _really_ weird.

I suspect that I'm going to spend a LOT of time tweaking the currents and winds based upon input from you guys, so it may be quite a while before I even get to climate...

----------


## Azélor

So to sum up the info on the planet:

You rotated the map so it spins like Earth
A day is 24h
A year is 240 days
Axial tilt 20 degree


About the currents.
The map looks pretty good. 
My only improvement would be the green current north of Artemis.
I would push it further east (assuming east is the right side of the map)
It makes the small red current bend, before mixing together.

----------


## Azélor

January pressure map:

Again in Artemis, I would push the high pressure system east, and maybe a bit south. The north west should not be affected much. 
The north pole should be more like a high pressure area. Such is the case on Earth because the pole is covered with ice. But since there is not much land up there, this doesn't really matter. 

Same thing with the south pole is July. The high pressure system should be expanded if there is an ice shelve.

July:

No high pressure system overland in the northern hemisphere, only over the water. Land is warmer and so the pressure lower.

The rest looks ok to me.

----------


## acrosome

As always, thanks for the awesome input.




> So to sum up the info on the planet:
> 
> You rotated the map so it spins like Earth
> A day is 24h
> A year is 240 days
> Axial tilt 20 degree


Correct.




> My only improvement would be the green current north of Artemis.
> I would push it further east (assuming east is the right side of the map)
> It makes the small red current bend, before mixing together.





> January pressure map:
> 
> Again in Artemis, I would push the high pressure system east, and maybe a bit south. The north west should not be affected much. 
> The north pole should be more like a high pressure area. Such is the case on Earth because the pole is covered with ice. But since there is not much land up there, this doesn't really matter. 
> 
> Same thing with the south pole in July. The high pressure system should be expanded if there is an ice shelve.
> 
> July:
> 
> ...


That's it?  Damn.  I was expecting a thrashing.  But I guess that I have done this a few times before with input from you and Pixie, and not a lot has changed since then.   :Smile:  

So, to feed back to you:

1. Have the current north of Artemis flow closer to the coast, as described.

2. Nudge the winter Artemesian high a bit southeast.

3. Put a high-pressure area in the center of the low-pressure areas I have around the poles in winter.  (Yes, there are polar icecaps.)  Should the southern one be confluent with the low over that southern continent (Ishtar) or kept separate?  If it's confluent, that will break the circumpolar low, won't it?  Is that "allowed"?  Or would the low bend down south around it, like the low around Greenland on the Earth map in your tutorial?  And what would that do to the nearby oceanic high?
Also, are there easterly (blowing east-to-west) winds around the extreme poles, then?

4. Crap, I think that I put that northern-hemisphere continental high in July when I meant to put it in January.  (I was basing it off of the high over Greenland.)  Would that make more sense?  And thanks for catching it!  And tame question about the low bending south around it applies, I guess.

Updated and prettified maps will follow.

----------


## acrosome

Here's the prettied-up currents:



Sorry it looks so busy; I used a brush of a set width to help me track my loops, to be sure I closed them.  I tweaked the current around Imdr so that it gets hit by a warm current, not unlike Europe.  Hopefully it'll have a mild climate despite being at 40-50 degrees latitude.  I tweaked a few other things, too, like the cold current hitting Artemis; I'd like a large desert there.  I sort of wanted western Beta to be _less_ desert but it's looking like there's no way to avoid that.

My warm currents seem to hit clusters of islands and ramify a lot.  (I'm basing that on Southeast Asia, Malaysia, Borneo, etc.)  Well, that and the rule of thumb that cold currents tend to be more cohesive, whereas warm currents break up like that.  I generally tried to put small currents in where they mattered, too.

Here are the north and south poles, to check that they make sense:

North:



South:



Having that large continent sitting just off the south pole does lead to odd stuff.  The circumpolar current has to mix with the warm water from that southern oceanic gyre.  So, no huge cohesive warm current hitting Ishtar- it'll be a very cold place.  Good fishing grounds, though...

I can probably neaten up that southern subpolar current, though.  The area would be analogous to Earth's north pole, with a lot of land nearby but not actually on the pole.  In Earth's Arctic Ocean the Beaufort Gyre is displaced significantly off of the pole.  I'll move some currents around at my south pole.

----------


## Azélor

There is a low pressure system south of Greenland because the water is much warmer. But it's high overland. 

Polar easterlies do exist but Wikipedia says they are weak and irregular, 



> 4. Crap, I think that I put that northern-hemisphere continental high in  July when I meant to put it in January.  (I was basing it off of the  high over Greenland.)  Would that make more sense?


Somewhat low in July. 




> My warm currents seem to hit clusters of islands and ramify a lot.  (I'm  basing that on Southeast Asia, Malaysia, Borneo, etc.)  Well, that and  the rule of thumb that cold currents tend to be more cohesive, whereas  warm currents break up like that.  I generally tried to put small  currents in where they mattered, too.


My guess it that slows down the currents (with possible shallow waters).
Meaning warmer water in the region. 
The water is pretty hot around Indonesia. But as hot as in the Red Sea.  :Cool:

----------


## acrosome

> There is a low pressure system south of Greenland because the water is much warmer. But it's high overland.


So, since my island is surrounded by fairly cold water, are you saying that it should _not_ have a winter high?  In fact you say to make it a _low_ in summer?  Or5 just "not high"?




> Polar easterlies do exist but Wikipedia says they are weak and irregular,


I guess that makes sense, since the subpolar _currents_ are weak easterlies as well.

The rest I understand- thank you.

I'll probably post pressure maps tonight or tomorrow.  If they check out I'll start on the associated winds.  And then- finally!- heat and humidity maps.

----------


## Azélor

Low but not the kind of low that would get you a monsoon. It's lower than the surroundings but not that low. 
In winter, if it's cold and large enough, it might have a high. If we are talking about the north island, I don't think it's big enough. 

I'm not sure the polar currents are right. Maybe they are too simplified? But I don't think it matter much climatewise. 
It's a lot messier: http://www.divediscover.whoi.edu/arc...nts-labels.jpg

Have you checked that map? https://upload.wikimedia.org/wikiped...erless%293.png

----------


## acrosome

> If we are talking about the north island, I don't think it's big enough.


That's what I figured.




> I'm not sure the polar currents are right. Maybe they are too simplified? But I don't think it matter much climatewise. 
> It's a lot messier: http://www.divediscover.whoi.edu/arc...nts-labels.jpg


I suspect, though, that Earth's arctic currents are so messy because it's a messy area.  There's lots of land and islands jutting in there making issues, with the North Atlantic current being forced into the area.  All of the fresh water creates problems too, of course.  (Apparently, arctic currents are significantly driven my salinity gradients.)  I'm going to re-draw my _south_ pole to be just a little more like it, but not quite that bad.  

Here, how is this?:



Messy enough?

My _north_ pole is so free of land that I think it would be _nearly_ idealized, as I showed previously.  Yes, the currents around the northern island and southern continent do look odd, but that's mostly because it's hard to get the deformation right at high latitudes- I'm no artist.  For now I just need something approximate.




> Have you checked that map? https://upload.wikimedia.org/wikiped...erless%293.png


Yes, that's my favorite source as a matter of fact.

Here's my final currents (I think):

----------


## acrosome

OK, if no one has commentary on these in a few days I can start on humidity and temperature maps:

January:



July:



Looks like monsoons in central Atla and southern Phoebe.

----------


## Azélor

It's not really wrong but the winds at the equator should blow toward the east a little bit more. There is definitely a west to east pattern.

----------


## acrosome

> It's not really wrong but the winds at the equator should blow toward the east a little bit more. There is definitely a west to east pattern.


Yeah, I left that little wind over the equatorial countercurrent out.  It's mild and predictable, and would have just cluttered things up.  I'll remember it when I'm doing climate.  (I didn't see them on the wind maps in your tutorial, so I figured that their effect was minor.)

EDIT-- Dammit, I missed some arrowheads, too...

All those highs in close proximity around the southern continent in July just sort of act like one big high, from what I see in my research, right?

----------


## acrosome

Step 5, Temperature.  Here are the Regions of Influence, using Azelor's colors.  This shows areas where hot, mild, and cold currents have an offshore wind, and the yellow is continental influence.  I do not believe that any of my continents could have the continental-plus influence.

January:



July:



I'm a bit confused about one thing in Azelor's method.  He says:




> *Hot current (red)* : areas affected by winds blowing from a hot current. Hot current have no impact in summer since the land is hotter than the water and it’s considered normal instead.


Does that mean that I should not mark red areas with warm offshore winds if they are between the Tropics of Cancer and Capricorn?  But his examples maps _do not do this_- they show all areas red, even between the tropics.

----------


## Azélor

It means you can ignore it. The hot current temperature group doesn't exist on this table https://www.cartographersguild.com/a...7&d=1454299273

----------


## acrosome

Yeah, I figured that part out- there is no hot current column in summer.  But (crap) I had mis-quoted:




> *Hot current (red)* : areas affected by winds blowing from a hot current. Hot current have no impact in summer since the land is hotter than the water and it’s considered normal instead. 
> Also, they have no impact between the tropics either.


The bit I _meant_ to ask about was that last bit about the tropics.  Obviously, summer has no hot current column, but there _is_ one for winter.  Do I just treat hot-influenced areas as normal if they are between the tropics in winter, too?

----------


## Azélor

Yes, the hot currents has an impact at higher latitudes only. And only in winter.

----------


## acrosome

Well, actually, since my tropics are at about 20 degrees, it turns out that your chart already has the hot and normal columns identical up to that latitude!  Score!  I don't have to worry about it- just use your chart!

----------


## acrosome

Here are WIP temperatures.  This is only the latitude and marine influences.  Next I'll add elevations.  I left all the edges sharp- I'll smooth everything after I add the elevation influences.

January:



July:



@Azelor: Your chart for this doesn't have red or dark red on it.  Where does that go?

Here's the chart I thought I was supposed to use:



As near as I can tell, elevation influences only lower temperature, so the red and dark red don't come out there.  Do those boxes in the upper right corner (continental influences) mean red?  But then where is dark red?

You posted this:




> [FONT="]
> Hot current: 20 orange 30 peach 40 yellow 65-70 green
> Mild current: peach 35 yellow 55 green 65-70 yellow
> Cold current: dark orange 5 orange 10 peach 35 yellow 55 green
> Normal: dark orange 20 orange 25 peach 35 yellow 55 green ...
> Con: peach 30 yellow 40 green 45 turquoise
> Con+: dark orange 15 orange 20 peach 25 yellow 35 green 40-45 turquoise 50-55[/FONT]
>   [FONT="]
> 
> ...


But there is still no dark red.

I feel like I'm missing something obvious as I scan through that thread.

EDIT-- You know what?  Looking at your example maps of Earth it looks like large continental influences tend to rather comprehensively cover continents that majoritively run east-west (in the summer at least).  Which both of my large continents do, run east-west.  I think I need to cover most of both of them with continental influence in the summer.  Then there would be more realistic red areas, if those boxes are supposed to be red.  And I finally found this:




> *Details on extreme temperatures:*
> 
> *Winter temperature placement:* 
> 
> *Take the second value for a very large continent
> 
> 
> Turquoise:  If there is an exchange of water north-south near the coast, its turquoise instead of blueBlue: appear on large landmasses above 50-55 but not on east/west coasts until 70. With a hot current the maximum could be 80-85. The coasts of a sea of ice or a closed sea are going to be blue above 50.Purple: it is usually in the center of a large blue area.  
> 
> ...


*Sigh*

Ok.  More will follow...

----------


## acrosome

I think that these larger continental influences will work better.  Or at least they look more like Azelor's example maps of Earth.

January:



July:



On to temperatures...

----------


## acrosome

Ok, before I smooth them does anyone see anything profoundly odd about these?

This is just latitude and maritime/continental influences.  I haven't added elevation influences in yet.

January



July



I let the Very Hot (Red) region on the equatorial continent (Aphrodite) extend south to 10 degrees because that's a large, dry interior.

----------


## Azélor

> Your chart for this doesn't have red or dark red on it.  Where does that go?


Indeed, dark red is not there. I was adding it afterwards, if there is a larger red region. It need to be really really hot. 
You don't have red anywhere, or maybe a little apparently. the reason its not that common on your map is because of land placement. You don't have that much land in the tropic-mid latitude range. 
The equator might get hotter in spring and autumn but we are not doing these 2 maps. 

Elevation will increase temperature if it goes below sea level. It is usually marginal on Barth but could be a factor in a fantasy world. 




> Ok, before I smooth them does anyone see anything profoundly odd about these?


In july, the transition to the red is too quick. you don't have any orange north of the area. And of course the southern continent will need a lot of adjustments. 
The green southern spot is a little big odd and I think it should be blue instead. Yet I expect that most of the east coast will be milder because of the ocean nearby. 
It tend to stay green near the coast and some parts in the south might be cold enough to turn blue.

----------


## acrosome

> Indeed, dark red is not there. I was adding it afterwards, if there is a larger red region. It need to be really really hot. 
> You don't have red anywhere, or maybe a little apparently. the reason its not that common on your map is because of land placement. You don't have that much land in the tropic-mid latitude range.


Yes, the only place with dark red on your example Earth maps is the western Sahara.  The area I marked dark red (severely hot) is mostly a large depression.




> Elevation will increase temperature if it goes below sea level. It is usually marginal on Barth but could be a factor in a fantasy world.


I filled that depression I mentioned, but if the climate comes out extremely dry I may actually re-do it as below-sea-level.  Great minds, etc., etc.





> In july, the transition to the red is too quick. you don't have any orange north of the area.


You mean to the north of it?  Yeah.  That's just the way things came out using your tutorial.  Obviously this world has peculiar climate that challenges the model.  I'll fix that when I start smoothing.  Frankly, I may have been overly aggressive with that cold current, anyway.  

There are several other spots with problems like that, too.




> And of course the southern continent will need a lot of adjustments. 
> The green southern spot is a little big odd and I think it should be blue instead.


You mean the bit on the southeast coast?  It came out that way because that's a cold maritime influence rather than a continental influence.  And, yeah, it looked peculiar to me, too.  Since you have validated my gut feeling, I'll fix it during smoothing.  (Really, I haven't adjusted _anything_ on these maps yet- this is raw output from your tutorial before smoothing and taking elevations into account.)




> Yet I expect that most of the east coast will be milder because of the ocean nearby. 
> It tend to stay green near the coast and some parts in the south might be cold enough to turn blue.


I did that because your example maps showed the continental influence in Siberia running all the way to the Pacific in winter, including Japan.  (There's actually not a huge current there, on the extreme eastern tip of the continent.)  That'll be an easy enough fix, though.  Should the large peninsula on the west coast be moderated a bit, too?

Thanks.

----------


## acrosome

OK, here are the base temperatures (i.e. altitude is still not taken into account), now that I have smoothed them out.

January



July



Is that better?  Or is the progression to red still too fast?  It's too fast, isn't it?

The central part (Thetis and Artemis) of that equatorial continent is about the size of North America, but that is a pretty long fetch of land to the west of it with only those few inland seas, so I figured it would be pretty dry and hot.  Did I assume too much?

For scale, Beta and Asteria cover about the same footprint as Australia.  Meaning their land area is somewhat less.

----------


## Azélor

I thin k it could be alright.

----------


## Pixie

I like where you're heading, acrsome. I wish I had a nick little bit more time to provide help/advice, but I'm reduced to lurking.

Still, I'll place my bet right now: the place to be, in this Venus of yours, is northwestern Artemis. Save me a patch of land in that long peninsula, for a house in the sun.  :Very Happy:

----------


## acrosome

> Still, I'll place my bet right now: the place to be, in this Venus of yours, is northwestern Artemis. Save me a patch of land in that long peninsula, for a house in the sun.


Buy now while land is cheap...

But that area is being hit by a cold current, so it may be more dry than you'd like.  Maybe it'll be a mediterranean climate, but maybe a desert.  We'll see.  I'm betting on Imdr.

Here are temperatures after taking elevation into account.  (Yes, it stills needs smoothing.  I'm working on it.)

January



July



The thing that I think is very interesting are those mountains in Atla that are so high that they are green, despite almost being on the equator.  That'll be a pretty big region of those juniper forests that are high on Kilimanjaro...

----------


## acrosome

I think these are the final temperature isotherms:

January



July



I had Wilbur spit out contours between Azelor's 1000-meter ones to try to guide my smoothing where I could.  

On to precipitation, which I suspect is going to need a lot of research for me to get it correct.

Also, considering how much buttpain was involved in just making these temperature maps I highly suspect that this GIMP-user is going to go crawling hat-in-hand to some PS-user to run the script on the last step of Azelor's method for me...

----------


## acrosome

Hmm.  If I nudge the axis of rotation just a bit, I get this:



Do you think that looks more interesting?  It gets that large continent off of the equator a bit, and also maybe makes Africa and Asia a better model for that equatorial continent.

Dammit.  Now I have to develop a half a dozen options with different axes and gets climates for them _all_, for comparison... 

 :Smile:

----------


## waldronate

But, now all of the climate work doesn't match!

----------


## acrosome

True.  Obviously, I'm going to finish it as-is, but I may play around with different axes of rotation later and see if anything speaks to me.

But that little change I posted gets both Alpha and Ishtar nice, warm currents to impact them, so they'd be more Europe-like.  Really, this looks good.  And if I nudge it maybe just another 5 degrees I bet I'd get massive monsoons in southern Thetis and Ovda....

But... a project for later.

----------


## zhar2

This is awesome!!! shame I never noticed before!

----------


## acrosome

Ok, I think that we all knew that I would do this.  I'm starting over again.

I nudged the planet 20 degrees to give it axial tilt, and to make for more interesting positioning of continents.  Here's the output from Wilbur:



Here is an elevation map, using Azelor's coloring:



Here are labels, for reference:



I'm changing some of the names that are too recognizable, but haven't gotten to them all.

You can see that the way I changed the axis of the planet gets Aphrodite (the continent made of Artemis, Thetis, and Ovda) off the equator, so I can model it best on Asia.  It also moves Chitaru north a bit, so that it isn't _completely_ a frozen wasteland.

So, as far as biomes go: I'm thinking that Aphrodite is *Asia, Atlu is *Africa, Chitaru is *Europe, Bethar and Dwibe and nearby islands are the *Americas, and I'm thinking that the northern half of the Ulfrun Islands will be *Madagascar.  But I'll see how climate works out before committing.  In particular, I need to do that to find a suitable *Australia.

Finally, I started on currents:



My biggest area of doubt is the Perchtan Gyre (the one cut by the map edge) where I have the cold current breaking up like that around the Ulfrun Islands (Zisa, Fea, and Bellona).  Cold currents tend to be more cohesive than warm ones, but obviously there will be some sort of currents around there.  Should I leave it as is, or should I not have the cold current ramify around the islands?  The channel between Zisa and Fea is narrow but deep.  The one between Fea and Bellona is shallow.

Once I get that figured out I'll fill in minor currents, and get on with things.

----------


## Azélor

I'm not sure about the biome placement but it would help to have a map with the continent names. I can't find Ulfrun islands. 

If the flow of water is small enough, it is possible to have mild current in the sea south of Atlu, flowing toward the pole along the western islands. 

It could be complex as it is possible to have cold and warmer currents flowing on top of each other, sometimes in different directions. I think this is the case in Western Australis for example.
 It can also be a seasonal thing. Since these are mainly surface currents which are greatly influenced by winds. But that is probably too complicated to be worth the time. And we are not even talking about the thermohaline circulation.

----------


## acrosome

Thanks.  More work will follow.  I'll monkey around with those currents south and west of Atlu.

Unless we cross-posted (since I do tend to edit and re-edit a bit) I think _did_ include a map of names and labels as you requested.   :Smile:  

Zisa, Fea, and Bellona are the Ulfrun Islands.

----------


## acrosome

How does this look for the Perchtan Gyre?:



It's sort of more "ugly", like you might expect currents to be around a lot of islands.

EDIT---

And here are completed currents.  I only included minor currents if they seemed important to figure out climate, somewhere:

----------


## acrosome

Hmm, the climate work is making a lot more sense than the last time.  Probably because with the 20 degree axial tilt added the continents equate _much_ better with Earth's continents, at least regarding latitude, so it just "looks right".


Here are pressure zones, yellow for low and green for high:

----------


## acrosome

OK, I'm retired from the Army now, started at my new job, and have time for my silly hobby again...

Here are winds:





As expected, with the axial tilt changed southern Ovda and Thetis will have significant monsoons.

And here are the influences:





The severity of the continental influence in the northern continent is almost reversed between the seasons, due to their odd shapes leading to encroachment by the hot and cold influences.  For instance, it's hard to justify having the continental influence extend southwest into the other continent the way that Asia's does into the Middle East and Africa in July.

I could probably narrow those influences and extend the continental zone, though, if others think that's more likey.

----------


## acrosome

Here are provisional temperatures:

January



July



I'll probably spend a bit of time beautifying these before moving on to precipitation- there are a few very unnatural-looking lines.  Criticism is welcome.

Here are elevations and a few land labels, for reference:



And currents:

----------


## acrosome

I'm working on precipitation.  This is all before taking elevation into account, since I want to be sure that my base maps are good, first.  Here they are, but I'll have some questions for the hive mind:


ITCZ

 

So, In the ITCZs that large massif in central Atlu is giving me fits.  Looking at the Andes it would seem that mountains that high are enough to block the rains.  So in particular what do you think of that rainshadow in January?  But it also has severe effects in July.

Hmm.  Hella monsoons in southern Thetis and Ovda.  I made the area between them a funnel, to get rains over the mountains to feed a Nile-equivalent river that showed up in Artemis when I ran it through Wilbur.  But I think I might need to make those ITCZ rains smaller, st least in Western Thetis.  Azelor mentions that Africa's is smaller because it's near the Sahara, and a good chunk of Thetis and Artemis should be desert.


High Latitude Dominant Westerlies

 

Should these rains curve eastward over Artemis as I show them? 
Would smaller landmasses like Boala, Fea, and Bellona get rains from the Westerlies?  Should I put westerlies on every little island in the correct latitudes?


Extratropical Storm Paths

 

I think that Chitaru and Manatum have too long a fetch to get these storms, like Africa on Earth.  Argument? 


Winter Monsoons

 

This is the one I'm probably most shaky on, since I don't really understand them.  I sort of waffled on placing them on every little island in the right latitudes, versus just ones near continents.  Which is right?

And my final question is, how do I combine all of these into a single layer in GIMP?  For the life of me I can't figure it out.   :Smile:

----------


## acrosome

Wow.

Uh, I just read through that thread with Azelor and Charerg refining the climate models.  I see that there is now a script for Gimp.  Yay!  But a lot of the model has changed and I might be back to the drawing board yet again.  Boo.  And there is another script- in Python- by AzureWings.  I'm currently searching through to see if there are intelligible instructions for it anywhere.

I think I rushed those pressure and wind maps in an attempt to get to the "good stuff" more quickly.  And more to the point I think I finally understand how to place red and dark red on the temperature maps, so I'm re-doing them more diligently.

----------


## acrosome

For those who might be interested, Azelor, Charerg, and AzureWings have produced some incredible tutorials and scripts for working out world climates.  Incredible, but at times hard to follow, that is, especially once they start collaborating after Azelor's basic tutorial is described.  A few years ago I thought that I was one of the better "climate guys" here but these fellows went all scientific and coder on me, and now I am but an acolyte.  Hopefully they'll put together something more formal at some point but they do all have day jobs...

A Reference Map for my terraformed Venus:



I tried to be more formal and diligent with the pressures and winds this time:

 

I think they're looking much better.  Still big monsoons in Thetis and Ovda.  Oddly, maybe a monsoon in eastern Chitaru?

My next dilemma is continental influences.  I have to decide if Boala or Bethar are large enough to have them. 
 Both Australia and Greenland have them, but neither of these landmasses is the size of Australia.  Bethar is about Greenland-sized, but on Earth Greenland's bit of continental influence is more associated with North America's than independent.

I don't think either would have them.  So here is what I have:

 

I modeled how the July continental influence on Artemis/Thetis/Ovda runs way west onto Northern Atlu on the way Asia's runs across the Middle East into North Africa, but the landforms are very different so that might not be realistic.  Thoughts?

I left off the warm influences in the tropics and the summer hemisphere since they have no effect, to keep things less cluttered in my mind.

With that, here are basic temperature isotherms WITHOUT taking altitude into consideration yet:

 

I'm still beautifying the final temperature maps.

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## acrosome

Final isotherms:

 

I'm much happier with how these look.

I tend to produce elevation contours _between_ the 1000-meter steps used in the tutorial to help guide me in making some of the lines less linear and more natural-looking.  So in the tropics in summer  I might have warmer temperatures crawl up an extra few hundred meters, or nearer the poles in winter have the colder temperatures crawl a few hundred meters lower, etc.  It keeps the isotherms from looking straight and artificial, and it's only a bit of extra work.  There is really not much of a remedy far north in that larger landmass, though- it's pretty flat.

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## randigpanzrall

definitively a very cute project and a good idea

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## acrosome

Here are some very basic precipitation maps.  Unlike the above steps I haven't done this a half-dozen times before, so I'm pretty shaky on it and would love some criticism.

I'm using the eight-color schema since I hope to use AzureWings' Python script to generate climates, but haven't yet added in the two driest colors (the equivalent of Azelor's "magenta penalty") because I just want to be sure that I have the basic precipitation right first.

 

And here's that reference map again:



Chitaru looks odd with heavy rains on both sides, because it catches both the extratropical storm path _and_ the westerlies.  Bethar is similar.  Does that seem right?

The large massif in Atlu still gives me fits.  Does that rainshadow look right?  And are those mountains in southern Atlu high enough to block the rains from crossing the continent?  They aren't as high as the Andes...

I'm also worried that my rainy areas don't seem to extend as far as Azelor's example Earth maps, but my terrain usually just doesn't seem to support that since high mountains are supposed to stop the rains.  Should I make any of these rainy areas bigger?  I'm especially looking at the north coast of Artemis, as well as Chitaru and Bethar, both of which have high central mountains.

Once I'm happy with this I'll add in the dry areas and do the elevation modifications.  I'm kind of excited to be on this last step, and then I can feed it all through AzureWing's script.  (And then I need to figure out the Holdridge life zones.  I know that there is a tutorial for that but I don't think there is a script.)

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## Charerg

Comparing to the reference maps from the Climate tutorial thread, the precipitation maps seem too dry overall. Especially Artemis, being in similar latitudes to Europe seems suspiciously arid. Also I'd make the summer monsoon stronger and reaching further inland in the Thetis/Artemis/Ovda continent.

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## acrosome

Yeah, that's why I was asking about Artemis.  I see what you're saying- I think I missed those 8-color reference maps you linked.

But do you think the monsoon would make it over those mountains?  The Himalayas seem to stop them.  Though, granted, Thetis and Ovda aren't quite as high as the Himalayas...

So more like this?  (Remember- I haven't done altitude corrections yet- this is just the basic maps.)

 

Asteria and Dwibe kind of puzzle me, too.  There aren't good analogs for them on Earth, i.e. at similar latitudes and not near larger continents.

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## acrosome

So here are finished precipitation maps:

 

So, running all of this through AzureWings' Python climate script... I keep getting color errors.  Working...

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## acrosome

Woot!



Now, some editing.

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