The sun heats different parts of the oceans unevenly. Uneven heating makes the air temperature above the ocean uneven. Remember that uneven air temperature causes wind. Water on the surface of the oceans is pushed forward by winds. The uneven heating of the earth's equator and poles causes winds. The hot air above the equator rises up and the cold air from the poles rushes to occupy this empty space and area and cold air from the surface of the sea occupies its space.