So, I'm a science-fiction writer, and I've got a weird one here: suppose you've got a planet that's mostly barren, with viable atmosphere, etc. conditions confined to a series of extremely deep rifts and depressions. Within those depressions, basically normal earthlike conditions prevail, so 21% oxygen, abundant water. They're up to sixteen kilometers deep, and outside of them the atmosphere as I conceive of it is quite rarified (i.e. top of Everest conditions). Of course, I am not a meteorologist, which is why I'm here, so possibly my picture there is implausible. For full disclosure, in case it matters, the planet is half earth mass, 80% earth gravity. The contiguous region of rifts and basins I am concerned with makes up ten percent of its surface, but spread out over most of a hemisphere (picture a gigantic spiderweb).
This is awkward without a map, but basically the "spiderweb" is divided in half, north to south, and those halves connected by a three thousand kilometer rift (closer to 2200 north-to-south, since the rift winds a lot). At either end of the rift stand two large basins; the southern one is roughly the size of Peru, with many connections to other basins, while the northern is more Iran-sized. The southern basin straddles the planet's equator and has a large sea in it. The northern also has a significant sea, but is naturally much cooler. An artificial canal runs through the connecting rift for trade purposes.
Now, by my primitive understanding of climate science, the southern basin should have much lower air density than the northern due to its receiving far more solar radiation. The differential will cause the basin to suck cold air through the connecting rift like a straw, generating a constant cool wind. Once that wind hits the warmer air in the south, it will precipitate moisture in the air, making the spot where the rift meets the southern basin extremely rainy. I'm guessing, based on vague intuition alone, that the overall balance of air in the system will then be maintained by the warmed air returning along the rift it came from, but at a significantly higher elevation. Is any part of this plausible?
Sorry for making it so complicated. This isn't the sort of thing I can just consult library books about, obviously. Thanks for reading!