Prevailing winds affect surface currents like the Gulf Stream because if the wind blows long enough a surface current begins to flow because when the air blows across the water some of it crashes into the surface water , pushing and pulling the water along.
Step-by-step explanation:
Prevailing winds blow predominantly in one direction. Therefore at the interphase between the atmosphere and oceans, where there are vast open spaces and no windbreakers, the winds will have an effect on the direction of the surface ocean currents. The prevailing wind, through drag, will cause the surface current to flow in the direction the wind blows.
The Gulf stream, for example, is driven from the Gulf of Mexico to Western Europe, by the trade winds and westerlies winds. This current has a major significance in influencing weather in Europe.