North and South poles
It causes them to deviate (different directions north and south of the equator) leading to the Coriolis effect.
Different water temperatures
Surface currents are created by air currents, earth's rotation, and positions of the continents.
The gravitational pull is different in the two hemispheres. Therefore rivers and water runs differently in the two hemispheres.
It causes them to scatter in different directions.
Two main reasonsthe surface of the earth is not smooth so currents have to travel in curved paths to get around obstaclesCoriolis forces - because of the huge distances involved the differences of forces due to the changes in the circumference of the earth at different latitudes causes currents to curve even if they are trying to travel in a straight line. Note: it takes huge distances - on the order of miles - to see any effect from Coriolis forces (- despite the urban folklore out there about drains swirling different directions in the Northern and Southern hemispheres. Hint - they don't) Unless your sink or toilet is miles across, you won't be seeing Coriolis forces determining the direction of swirl as they drain.
Surface
The two causes of ocean currents are wind and the rotation of the earth(etc) The wind blows which makes the currents in the water and the rotation of the earth(gravity) makes currents in the ocean currents. Luaye Sharawy
The gravity of the Sun and the Moon causes tides. Waves are caused by the wind. Currents have a variety of causes, but differential heating of different parts of the Earth by the Sun, modified by the coriolis effect of the turning Earth is the main one.
In the northern hemisphere, ocean currents generally flow clockwise, while in the southern hemisphere, they flow counterclockwise. This is due to the Coriolis effect, which causes moving objects to be deflected to the right in the northern hemisphere and to the left in the southern hemisphere.
its caused by the moon
In electricity? High voltage ,high currents. Low voltage, low currents.