Sorry again for being quiet. I got a little wrapped up in my investigations of wind. Wind is a complex thing, and I have to make a decision on how realistic I want to model it.
In order to do that, we have to think about what modelling wind gets us. What does wind do, in world building terms? I think it does two things. One (and of lesser importance), it moves a bit of topsoil around. Not much, really, in comparison to what water will do, but a bit. So we'll do that (but no effect on the underlying bedrock).
Two, it moves water vapor around. This is the one that is important, I think. We'll add vapor to a tile based on water content and temperature, then move it based on wind speed and direction (and subsequently drop it as rainfall if it moves to an area of lower temperature and/or higher elevation).
So anyway, given that, I think we need only to model a fairly simplified version of wind. If you look at any global wind map, there are six major zones, three above the equator and three below (the whole thiing is caused by differing tempatures and something called the coriolis effect).
So, I think we'll just set up wind direction like this:
Zone 1 - North pole to ~60 degrees: South to Southwest
Zone 2 - 60 degrees to 30 degrees: North to Northeast
Zone 3 - 30 degrees to Equator: South to Southwest
Equator - Doldrums - no wind
Zone 4 - Equator to 30 degrees: North to Northwest
Zone 5 - 30 degrees to 60 degrees: South to Southeast
Zone 6: 30 degrees to South pole: North to Northwest
Not sure if I want to try to gradient between the zones, or if we can just use a sharp cutoff. As for windspeed, I'm not really sure of that either. Maybe it's not so important, we can just use direction and move water vapor one tile per iteration rather than trying to factor in speeds?
What makes wind complicated in the real world is the temperature differences between land masses and ocean. I don't know that we want to mess around with that (although as a result we will end up with somewhat unrealistic occurances of on-shore windflows rather than the much more common off-shore windflows).
Anyway, thoughts are welcome.