Cool to hear you're interested in my worldbuilding excel magic, srm038. I might post about it once I finish the reworking of Theia's world climates.

I've done a complete rework of the pressure and wind systems, taking the large polar ice caps into consideration, and making three strong circular wind systems to gird the globe. Hopefully this makes sense.

JANUARY WINDS & PRESSURE
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JULY WINDS & PRESSURE
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Based on those, I made new precipitation maps. Perhaps my great continental swirls are a bit of a stretch, but they're cool, at least.

JANUARY PRECIPITATION
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JULY PRECIPITATION
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I also reworked the temperature from scratch, paying a lot closer attention to the many, many posts of the tutorial thread. Using layers of 50% grey, set to Screen for colder effects and Multiply for hotter, and masks drawn in pencil, I was able to create a greyscale map under a Gradient Map adjustment layer, set to the correct temperature colors. By adjusting FILL, I could get them to match the colors and get a temperature progression that felt right, corresponding to Azélors tables. In addition to latitude and elevation, I've factored in ice sheet albedo, ring shadow, continental and three types of maritime influences. By adjusting the grey level of the base color, I could adjust everything to fit the general temperature level of my planet, giving me this result:

JANUARY TEMPERATURE
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JULY TEMPERATURE
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And, after uninstalling GIMP 2.10 and installing GIMP 2.8, I even managed to get the 6-step script to work - producing this awesome climate zome map.

THEIA KÖPPEN CLIMATE ZONES - second draft
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Now I can adjust and rework to my heart's content. but I'm pretty happynow. I've got deserts, steppes and rainforest where I want them, mediterranean climate in the right spots, and a nice Dfb region for my longship-sailing matriarchic society.

I see I still have to do some tweaking to get my highland river region out of the same Dfb area, and into something more like Cfb, but hey, I'm super happy to finally have cracked the code, being able to make sense of this.

-Niels