First of all, i really like your map. The continets have very appealing shapes. Looking forward to this map.

Second of all, i am sure some members will soon explain this to you in awesome detail. There are a lot of very knowledgeable guys around here.
For the meantime, take a look at this: http://www.sci.uidaho.edu/scripter/g...wind-belts.htm

On our world, the equator has low airpressure (the air is ascending) and the subtropical line at around 30 degree has high pressure (air descending). Take a look at the link above...there are a lot of nice pictures. And if you want to have more detail, there is a ton of info if you google for "wind belt", for example.

Hope that helps a bit.