Subject: Sulfur dioxide and acid rain

I see many references to sulfur dioxide combining with atmospheric water to 
form "dilute sulfuric acid" (for example, see answer regarding plasma 
dispelling fog.) I believe that sulfur dioxide disolved in water makes a 
dilute "sulfuruos acid" (H2SO3). As I understand it, sulfur dioxide must be 
oxidized by UV/ozone or something to form sulfur trioxide (SO3) before it can 
combine with water to form sulfuric acid (H2SO4). Is this correct, or can SO2 
combine directly with water to form sulfuric acid (H2SO4)? Is sulfurous acid 
the culprit in acid rain or is it sulfuric as is commonly stated?

Re: Sulfur dioxide and acid rain