Flat world would change everything, naturally! but basically speaking, warm waters at the equator head toward the poles, while cold waters heads toward the equator and the spin of the world makes that clockwise in the north hem and counter in the south hem. The resulting affect is that currents on the west coasts of continents tend to be cold (less evaporation and drier) while the east coasts are warm water (more evaporation and wetter).

Looking good!