Patagonian Desert

[yurell]

I've just a quick question about the Patagonian Desert. I noticed that most major deserts are to the west of mountain ranges, which is where their rainshadow is. However, the Patagonian is to the east of the Andes instead, and was wondering why the rainfall in that region was going that way rather than the other. Is it because the South Pacific Ocean to the west is warmer than the South Atlantic to the east?

[Tass]

http://en.wikipedia.org/wiki/File:Map_p ... _earth.png

[eternauta3k]

The Andes eat up humidity from the West, while the middling terrain eats up humidity from the East. That's my vague recollection of Geography class.

[yurell]

Interesting, so it's a prevalent wind pattern of extreme latitudes — thanks!
So if I understand correctly, high pressure at the poles causes it to rotate west-east, but as it warms the pressure lowers, making the Coriolis effect push the equator half east to west (anti-cyclonic?). We never did much meteorology in geography, so I'm rather ignorant of this field.