New Map Generator and Aridity

[ghost]

The new map generator tends to create more contiguous chunks of land, which is better than the noodle-generating stock engine, but it also results in longitudinal stretches of arid land. This can sometimes be devastating to the AI's early development since it doesn't have the privilege of restarting the game for a better start, ha-ha. I played around with some quick map edits to try to determine what was going on, plus looked at the canonical "Map of Planet" to see what an intentionally designed map looks like.

Wind blows towards the east on Planet, and moisture comes from bodies of water apparently of any size. I made broad stretches of land at the same elevation band with sea to the west. The first tile on the western coast would be moist, then every inland tile beyond would be arid. When I raised an elevation slightly inland, the windward side would catch moisture as expected and create moist/rainy tiles. Interestingly, though, tiles directly east on the leeward side of the elevated tile(s) would turn from arid to moist.

So it appears that the weather model won't have clouds release any moisture until they hit an elevation. Then it will release most of the moisture on the windward side and a little bit after that. The Map of Planet is designed with a lot of undulating terrain that changes elevation bands often enough to create a lot of moist tiles with some rainy and some arid. To me this seems like the "natural" state of things.

I took a look at map.cpp but I'm too dumb to get any of it.