Geographical Help Needed

[Azélor]

It's the deserts found around the tropics http://www.google.ca/imgres?imgurl=h...FYlpPgod4iMJQQ

But we could also say that the poles are latitude deserts since poles are cold and dry.

This exclude Patagonia and Central Asia as they are too far away from the tropics.

[AslanC]

That explains it better for me. I appreciate that.

Now my concern is how air flow would go, given that map has large swaths of land separated by mountain ranges, with water on either side... does that play into the desertification?

Cheers!

[Azélor]

Mountains do no stop the air flow. They might make it slower of deviate it but it can still go through.
But they prevent the moisture from moving to the other side. That's the rainshadow effect mentioned by Chick.
To decide whether it's rainy of dry, you need to figure the direction of the air flow.

Winds depend mostly on 2 things: the global air circulation http://www.ux1.eiu.edu/~cfjps/1400/circulation.html
and influenced by the differences in temperature, the border between the air cells will shift to look like : http://www.google.com/imgres?imgurl=...FYk0PgodKmwCLw

air=low pressure cold=high pressure
it's tricky since deserts are dry despite the fact that they can be at low pressure. But the Sahara and Arabian peninsula receive air from Central Asia and Iran. The winds carry almost no moisture.
Somalia is a special case, just ignore it for now.