Ocean water is not perfectly still due to the presence of various forces and factors that constantly influence its movement. The primary causes of oceanic movements are tides and waves.
Tides are the regular rise and fall of the ocean's surface, caused by the gravitational pull of the Moon and, to a lesser extent, the Sun. The gravitational attraction between these celestial bodies and the Earth creates a tidal force that causes the water levels to change. As the Earth rotates, different parts of the ocean experience varying gravitational forces, leading to the formation of tides.
Waves, on the other hand, are primarily generated by the wind. When wind blows across the surface of the ocean, it imparts energy to the water, causing it to move in a circular motion. This circular motion creates waves that propagate across the ocean. The size and strength of the waves depend on factors such as the speed and duration of the wind, the distance it travels, and the area over which it blows.
In addition to tides and wind-generated waves, other factors contribute to the movement of ocean water. These include ocean currents driven by differences in water density (caused by variations in temperature and salinity), underwater topography (such as ridges and canyons), and the rotation of the Earth (which induces the Coriolis effect, influencing the direction of currents).
Overall, the complex interplay between gravitational forces, wind, temperature, salinity, and the Earth's rotation leads to the dynamic nature of ocean water, with tides and waves being prominent manifestations of this constant movement.