In a nut shell...
Because of the dihedral, during a turn, the down going wing will produce more lift than the up turn turning wing. This then trys to roll the aircraft out of the turn. This is positive static lateral stability.
The down going wing produces more lift due to the effect of the slip stream in a turn.
To be honest is very difficult for me to explain the answer to your question without drawing a diagram of how the dihedral effects the AOA. Sorry.