Theia revisited - Climate check (WIP)

[nwisth]

Hi! My name's Niels, and I'm writing a novel.

I started a little over a year and a half ago, and in that time I've been doing a lot of worldbuilding - which, of course, takes maps. I just finished the first draft of the first 90k word part of the first novel in the series (yeah, why not be stupidly ambitious, lol), but as I was browsing the guild forums looking for something to help me make my local area map of the place my second storyline is taking place, I found this amazing climate tutorial by Azélor.

Now, I have prided myself on taking the time to build my world of Theia as realisticly as possible - but when it comes to climate zones, I have to admit it's been mostly guesswork. I want to find out how far off I've been, and if I have to rethink any of the civilized areas where my story takes place.

First, let me share what I have so far:

THEIA (here in HEALPix-projection):

Theia-HEALPix-projection.JPG

Theia is an earthlike planet, orbiting YBP 1194, a solar twin 2772 light years from Earth. This star is incredibly similar to our sun, but unlike our system it has a massive exoplanet about the size of Saturn, in close orbit around the star. Every seven days, it casts it shadow on Theia, dimming the light by a noticeable amount as the black spot travels across the solar disk.

Theia is smaller than Earth. It has a diameter of 9040 km, and circumference of 28400 km, which gives it a diameter that's 0,7095 of Earth's. That means it has a lot smaller surface area - while Earth has 510.1 million square km, Theia only has 256.8. Since the planet is very iron rich, however, its density is 1,4 relative to Earth's - and has a surface gravity of 1G. It also shares the Earth's axial tilt, to make it easier to replicate Earth-like seasons.

I used the excellent Worldbuilder tool by Experilous to create my land masses. It's a shame it's discontinued - the program really rocked, taking care of tectonics and giving me an elevation map as well as a temperature map based on elevation and other input parameters. Theia has a ring, whose shadow travels up and down the globe due to the axial tilt - which makes a lot less light reach the surface in winter - so I decided to make the world colder and the ice sheets bigger.

After going through a lot of iterations, I found a look that spoke to me, and could continue.

This is the first equirectangular biome, elevation, and temperature maps, straight from Worldbuilder, showing all the continents of Theia:

BIOME:
Equirectangular 2 - Biomes.png

ELEVATION:
Equirectangular 2 - Elevation.png

TEMPERATURE:
Equirectangular 2 - Temperature.png

Worldbuilder also made a wetness map - but I didn't know enough to make sense of it, and as a result, the biome map was hard to interpret. I decided that I had to create my climates manually. Armed with google and wikipedia, I started researching wind and seasonality, and started working in Photoshop.

I decided to use the simplified model, with bands of low and high pressure following the circles of latitude, and winds moving between them. I ended up dividing the world in temperature zones. I read that the sea retains its heat level throughout the year, while it changes overland, so with some clever use of masks I created wind and temperature zone maps for the equinoxes and the two solstices, where I moved the effects of the latitude circles and the following winds up and down, respectively:

SPRING/AUTUMN (with circles of latitude in their proper place):
Theia-Equirectangular-WIP-process-winds-temp-spring.jpg

SUMMER:
Theia-Equirectangular-WIP-process-winds-temp-summer.jpg

WINTER:
Theia-Equirectangular-WIP-process-winds-temp-winter.jpg

Based on these, I masked out the heat map from Worldbuilder and used reds and yellows to paint the heating and cooling from the currents, as well as modify the color according to the seasonal temperature band maps I'd just made:

SPRING/AUTUMN Modification layer example:
Theia-Equirectangular-WIP-process-tempmod-spring.jpg

The green is just to make the added colors show up. They're set to Soft Light with about 50% transparency. Here are the summer and winter heat maps, after modification. The ring shadow is also present as a yellow reflected gradient centered from 30 degrees.

SUMMER HEAT MAP:
Theia-Equirectangular-WIP-process-heat-summer.jpg

WINTER HEAT MAP:
Theia-Equirectangular-WIP-process-heat-winter.jpg

Now, being very happy with this, I ignored trying to seasonalize the ice caps, and simply started researching climate types, trying to figure out what would go where. I also wanted it to look better - and how to add rivers? More research led me back here, where I found Arsheesh' fantastic tutorial for GIMP & Wilbur.

Wilbur was awesome. I put the height map from Worldbuilder into Wilbur, and after fumbling around a while, I managed to get some rivers:

Theia-Equirectangular-WIP-process-wilbur.jpg

At this point, Theia was really beginning to come alive! I couldn't wait to start telling stories in it. I recolored the result to give me a nice grassland base color, and then used various brushes and masks to paint in mountains, jungle, desert, forest and plains in the areas where I figured the conditions matched those of Earth:

Theia-Equirectangular-WIP-process-terrain.jpg

Here it was - a world of my own, full of endless opportunity. But I had to zoom in. In my story, humanity only exists on one continent, having developed from a single point of origin. I picked the most interesting-looking one, and started anew, running the height map through Wilbur once more, adding a large inland sea in the lowest elevated basin. My continent-map will have to wait for another post, but here's a closer look at it, in the Lambert Conformal Conical projection (made with NASA's awesome G.Projector):

Theia-Lambert-Conformal-Conic-1.jpg

I've tried my best to place realistic climates. I decided to simplify, so instead of using Köppen, I divided my continent map into Sub-Arctic (Scandinavian), Coastal Temperate (French/British), Chaparral (Mediterranean), Dry Sub-tropical (Spanish/Maroccan), River Highland (Inland temperate rainforest), Highland Steppe, and Tropical regions. By counting hexes and using historical European population figures from 1000-1500, I found the population density my various countries could support, and have made an enormous excel sheet which calculates everything from average distance between villages to happiness scores. But that's probably not something you want to hear about on a cartography forum.

My point is, I have done a lot of work to try and make this as realistic as possible. But, seeing the Köppen climate tutorial by Azélor. I realized there was a lot I hadn't done, and a lot of guesswork. How about precipitation? How about a height map that actually shows height above sealevel? What will my map look like, if it goes through the scripts made by these master cartographers?

I have to know how far off my guesses are. Can I manage to get a detailed Köppen map if I follow the seven-step program?

I will try, and post the results here.

-Niels