[Award Winner] Where does the wind blow?

[jbgibson]

Did I mention I stretched your map to show 1 1/3 diameters? Makes it easier for me to visualize this stuff if I'm not having to mentally wrap vectors left edge to right edge. I'm also assuming the north and south edges of your world map don't run all the way to the poles.

Since I don't want to presume to repost someone else's map, here's Paidixira and Megalaos. Well, except for the fact I am using a simplified Megalaos map as the base for the first part of this tut :-).... I have been referring to the continent map further down that thread for climate preferences - the one where The Cusp is mostly desert.

Now, given that these highs and lows space themselves out apart from one another, there's multiple arrangements that would be about as plausible. Knowing that you want the midwest of Paidixira to be dry, we'll say that's where the main continental high lurks. I'll go further in a minute, but like you can guess from the way the wind bands slant, northern hemisphere highs have an outflow that spirals clockwise. So a high over western Paidixira leaves that dry-ish air curving down across the SE of the continent too - I see you have a desert across The Cusp. We try to accomodate :-). Air crossing land doesn't add much moisture, so there's not a lot of rain there in the SE. Those crisp Times Roman highs and lows are in reality very blobby, and shift around. Maybe some of the winter half of the year there's two weak highs, one on either end of the continent.

In the (northern) summer, you might get an arrangement like so:

[jbgibson]

The N hemisphere lows are counter-clockwise spiraling inflow. I can plausibly imagine a couple of weak lows bracketing Paidixira like shown, or one larger one more centered on it. In either case, the combination of clockwise outflow on a high and counterclockwise inflow on a low still conspire to drag wet air across those mountains to dry it out before it gets to the desired deserts. I'm thinking the pair get the SE dryer, so your depicted The Cusp desert is sensible.

I'm sitting here twisting imaginary airmasses with my hand above the screen. Son #3 is asking if I'm drawing doorknobs :-). It's time to do some more realistic wind than those idealized belts. Southern hemisphere highs and lows keep the same in vs out, only the spiraling is opposite-handed. Crossing the equator you can apparently get a shifting of 'handedness' of the curve to the winds, thanks to the coriolis force. Another rule of thumb I haven't mentioned is that equatorial belt labeled as the doldrums on the ideal globe is more of a trough than a string of pits, if you want to visualize pressure as height ("low", "high" - works for me). And the effective line of that 'solar equator' is called the intertropical convergence zone, and bends farther away from the real equator over land than it does over water. The 60-degree(-ish) low area can be a trough too, especially in a hemisphere's winter. Honest, I got all that stuff from climate and metrology books & sites... any wrongness is me, any rightness is luck, or somebody else's research.

[jbgibson]

Make some arrows. Hmm - The bigger ones will do for a crude set of vectors. I used smaller ones for a lot of detail on the Aurora Wind Maps (see far below), and it drove me nuts. You guys who can drop in a curve with arrowhead with a couple of clicks, please do so and make prettier pictures than this.