How does the sea water flow?

Ocean current As far as ocean current is concerned, both surface current and subsurface current are marine elements that researchers often pay attention to. The normal movement of seawater is ocean current.

The earth's surface is not evenly heated, and the solar radiation is strong and the temperature is high in low latitudes near the equator. With the increase of latitude, the solar radiation becomes weaker and weaker, and the temperature gradually decreases. At the South Pole and the North Pole, we entered a world of ice and snow. Due to the flow of air, the temperature in the equatorial region is very high, and the air rises and flows to the poles. Therefore, an atmospheric circulation is formed between the equator and the poles. This kind of airflow is our most common wind. Due to the influence of the earth's rotation and other factors, the original due south and due north wind direction has changed, forming a wind belt on the earth's surface.

When the wind blows the water, the seawater flows away somewhere, and the adjacent seawater is replenished immediately, forming an ocean current, which is directly generated by the wind and is called wind ocean current.

So, are there any currents in the ocean caused by other reasons besides wind currents? Of course there is. For example, due to the uneven distribution of seawater density, the density flow of seawater flows; The tidal current that moves horizontally when the sea water fluctuates. In fact, ocean currents caused by a single cause are rare, and ocean currents are often the result of a combination of many reasons. Once the ocean current is generated, it will be affected by factors such as the depth of seawater and the change of topography. In order to study ocean currents, scientists classified them. According to the causes, ocean currents can be divided into wind currents, tidal currents and density currents. According to the position, it is divided into coastal current, equatorial current and polar current, and according to the depth of the current, it is divided into surface current and bottom current. According to the comparison between the ocean current temperature and the water temperature flowing through the sea area, people also divide it into warm current or cold current. Stranger still, there are upwelling and downwelling, which can fluctuate up and down. So there are generally three kinds of ocean currents: the seawater movement caused by different seawater densities is gradient current. Under the action of sea breeze, sea water is moved into airflow by the "pulling force" of the wind; Seawater movements caused by long-wave movements, including tides, internal waves, false tides and tsunamis, are all long-wave tidal currents.

Tide. Tide is the periodic fluctuation of seawater level caused by the attraction of the sun and the moon to the earth. In many coastal areas, the sea level fluctuates twice a day due to the gravity of the moon and the sun. The degree to which all water bodies are affected by tides depends on their size and shape. The average tidal range in the world is 0.76 meters. The lower tidal range is Lake Superior, only 6 cm. On the contrary, in the Bay of Fundy, Canada, the maximum tidal range is13.5m.. Today, tidal research has been more systematic and complete. What is important is that it is of special significance to navigation, port construction and military affairs, so it attracts attention.

Waves. There are all kinds of waves in the ocean, from surface waves generated by the wind to tidal waves generated by the gravity of the moon and the sun, in addition to internal waves generated by the density gradient layer that is invisible on the surface and drops sharply. And tsunami, storm surge and other long waves that are very rare in our laboratory.

In addition, seawater temperature, density, sound speed and ocean depth are also the most common basic elements in physical oceanography. It is also of special significance to the ongoing marine engineering, mariculture and marine environmental protection. The measurement of ocean depth is particularly important; Because all meaningful oceanographic measurements must be located in depth, latitude and longitude coordinates.