Ocean currents are continuous and directed movements of water produced by multiple factors. Currents can happen in rivers, lakes, swamps and other water systems, although in the oceans, because of their size, a higher number and stronger currents exist.

These ocean currents flow over long distances and sometimes significantly influence life on Earth. What changes their direction and strength? The topography of the seabed, their interaction with other currents, and the configurations of the shorelines.

Causes of ocean currents

The effect of several factors acting over the water that generates currents like the wind, the rotation of the Earth, the gravitational force of the moon, differences in temperature and salinity, the topography (shape) of the seabed, the heat from the sun, etc. Let’s review the three most important factors that generate currents:

1. Wind.

Drives currents that are near or on the water surface. Seasonal winds push surface waters away from the coast, so the water rises in the western edges of continents.

2. Tides.
Tides, created as the result of the gravitational pull of the moon and the sun, create currents near the coasts, bays, and estuaries. Their pattern is regular. Therefore changes are predictable.

3. Thermohaline Circulation.

Density differences, due to salinity and water temperature differences, drive this flow. It causes the bottom topography influence on deep currents.

Types of ocean currents:

Surface Currents.
The wind usually drives them and are almost 8-10 percent of ocean water. In the northern hemisphere, they move in a clockwise direction, but in the southern hemisphere, they move in the opposite direction. These waters are rich in nutrients, causing a large population of marine life to inhabit there.

Types of ocean currents.

Surface currents can be of two types:
1. Warm, ranging from the tropics to high latitudes and
2. Cold, originating in polar and temperate latitudes and flow toward the equator.

When several ocean currents are connected, they form the so-called gyres, in which water moves in a circular pattern while maintaining the clockwise motion in the northern hemisphere and the opposite in the southern hemisphere.

Deep Currents.
Also called submarine rivers; they flow at more than 100 meters deep and move because density differences about salinity and temperature.

Coastal Currents.
The wind blowing along the coast affects the waves and these, in turn, the currents.

Tidal Currents.
They are the result of the high tides and the low tides. When tides close to the shore move vertically, up or down, they move water horizontally, creating currents. These are the only type of currents generated by the gravitational attraction between the sun, Earth, and moon.

Ocean currents affect the regional climates, marine life, and the cycle of nutrients in the water.

The importance of Ocean Currents.

Ocean currents affect the regional climates, marine life, and the cycle of nutrients in the water. In this regard, the transport of nutrients promotes the prosperity of many species of plants and marine animals, and sediment transport or harmful particles in the surface currents gives an overview of the effects of pollution and its causes.

Moreover, the preparation of navigation by observing the direction of the currents ensures safe travels. In the case of shipwreck, rescuers can determine the location of the missing persons.

It is also important to note that the currents generate high temperatures in parts of Western Europe and promote plant and animal life in Antarctic waters.

Examples of ocean currents.

In the world, there are several ocean currents, like
– Antarctic Circumpolar Current.
– Eastern Australian Current.
– Gulf Stream.
– California Current.

Definition of Tides.

Tides are increases and decreases in the sea level. Surely you’ve noticed this because it is a common and easily witnessed phenomenon. For a while, a boat floats near the shore, and after a few hours, the boat rests on the sand. When this occurs it is said that is low tide, and when the opposite happens, it is said that the high tide.

There are four stages of tides:

1. Sea level rises gradually over several hours.
 Flood tide.
2. The water level is at its highest level.
 High tide.
3. Sea level falls slowly for several hours. Ebb tide.
The water stops falling reaching its lowest level. Low tide.

The tides are not unique in the oceans; they can occur in other water systems as long as the required conditions happen.

Types of tides

There are two types of tides: high tide and low tide. Also, tides may be semidiurnal or diurnal. These tides have one tidal cycle per day, meaning one low tide and one high tide, while the semidiurnal tides have two high tides and two low tides per day.

Causes of tides

The tidal phenomenon was the subject of various theories until Sir Isaac Newton in 1687 explained that tides are the result of the gravitational attraction of the moon and the sun. However, first things first.

Some factors influence tides called tidal constituents. They are the rotation of the Earth, the position of the moon and the sun to our planet, and the shape of the shore and the seabed. Thus, the duration of the tides and their amplitude depend on these components and can last hours.

Definition of Tides

According to the mass of the objects, and the distance between them, the gravitational force varies; this is the fundamental principle for understanding the cause of tides. Knowing this, the moon’s gravitational pull on the Earth is the primary component. The moon’s gravitational pull is so strong that it “pulls” the oceans, creating a lump. This pull is stronger on the side of the planet facing the moon because it’s where the moon and Earth are closest.

The force of inertia (property of staying in rest or motion) tries to keep the water at its normal level. Also, Earth rotates continuously generating a centrifugal force which causes oceans to protrude on the on the opposite side of the moon.

Tides are essential to generate tidal energy through turbines or other methods that generate electricity.

The inertia exceeds the gravitational pull and in short, two bulges of water that align with the moon are created as the Earth turns.
Oceans protrude two times in one period when they are on the side of the Earth closest to the moon and again when they are on the far part of the planet. In coastal areas, high tide occurs approximately every twelve hours and 25 minutes. If the moon is above your head and you’re on the coast, you should see high tide.

Tides are essential to generate tidal energy through turbines or other methods that generate electricity. Tidal energy is a renewable, clean energy and contributes to sustainability. Tides are also relevant for sea travel, and thus they are placed in nautical charts, indicating the direction and the speed that ships must observe during high and low tides.


Quick Facts:

The Tsunamis, are not related to tides.

There are tide-measuring stations that measure, describe, and predict tides.