There has to be a force applied to something to make it start moving. (This principle is known as Newton’s Second Law of Motion in physics.) So, in the most general sense, water moves because some force has been applied to it. The most important forces on the ocean are from pressure gradients (applies a force directed from the high pressure toward a place with lower pressure) and winds. The pressure gradients can happen when the winds push water toward a place where it “piles up”. Pressure gradients can also happen when water gets cooled, which makes it more dense, or heated, which makes it less dense.
There are two main causes of the ocean’s motion. The simplest to understand is the effect of the wind. As the wind blows on the water it tends to push it forward much the same way soup in your soup bowl would move if you blew across the bowl. However, the ocean is on a rotating earth and the effect of that rotation is to divert the direction of the flow. When that’s properly taken into account we can actually predict the large currents in the upper 2000 meters of the ocean. The ocean is also heated at its surface in the tropics and cooled at higher latitudes and that heating and cooling also drives a circulation as the cool and heavier water sinks and the warmer water rises.
There has to be a force applied to something to make it start moving. (This principle is known as Newton’s Second Law of Motion in physics.) So, in the most general sense, water moves because some force has been applied to it. The most important forces on the ocean are from pressure gradients (applies a force directed from the high pressure toward a place with lower pressure) and winds. The pressure gradients can happen when the winds push water toward a place where it “piles up”. Pressure gradients can also happen when water gets cooled, which makes it more dense, or heated, which makes it less dense.
There are two main causes of the ocean’s motion. The simplest to understand is the effect of the wind. As the wind blows on the water it tends to push it forward much the same way soup in your soup bowl would move if you blew across the bowl. However, the ocean is on a rotating earth and the effect of that rotation is to divert the direction of the flow. When that’s properly taken into account we can actually predict the large currents in the upper 2000 meters of the ocean. The ocean is also heated at its surface in the tropics and cooled at higher latitudes and that heating and cooling also drives a circulation as the cool and heavier water sinks and the warmer water rises.