Atmospheric circulation Explains why the Earth's surface winds such as the NE Trades blow diagonally rather than purely in the north-to-south direction.
Motion of cyclones Part of the reason why air flows either clockwise or counterclockwise, depending on the hemisphere, around low pressure in the atmosphere.
Ocean circulation Explains the gyres, the largest features of surface ocean circulation. Part of the reason why surface gyres circulate clockwise or counterclockwise, depending on the hemisphere, around central "hills" of water.
Ekman transport Explains why regional surface water set in motion by wind flows in a slightly different direction.