Marine popular science knowledge

The ocean is the floorboard of the widest water body on the earth. The central part of the ocean is called ocean, and the marginal part is called sea. They communicate with each other and form a unified water body. ?

The earth's surface is divided by the mainland into vast interconnected waters called oceans, with a total area of about 360 million square kilometers, accounting for about 7 1% of the earth's surface area, with an average water depth of about 3795 meters. The ocean contains more than1350 million cubic kilometers of water, accounting for about 97% of the total water of the earth, and only 2% is available for human consumption.

Extended data:

I. Distribution of ocean currents:

Although the distribution and direction of ocean currents are very complicated, there are still laws to follow.

(1) A low-latitude circulation is formed between the equator and 40-60 degrees north and south latitude, and its flow direction is clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. The western part of each circulation is warm current, and the eastern part is cold current.

(2) A high latitude circulation is formed north of 40 or 60 north latitude. Its circulation direction is counterclockwise, with cold current in the west and warm current in the east.

(3) The North Indian Ocean north of the equator belongs to monsoon current because it is located south of the Tropic of Cancer. In winter, the northeast monsoon blows, the surface seawater flows westward, and the ocean current flows counterclockwise; In summer, the southwest monsoon blows, the surface seawater flows eastward and the ocean current flows clockwise.

(4) The east-west ocean currents are all warm currents except west wind drift in the southern hemisphere. ?

Ocean current has a great influence on the coastal climate of the mainland, and the area where the cold current passes has the function of cooling and dehumidifying the climate; Warm current has the function of warming and humidifying the climate along the way.

(5) At present, it has been found that there are three uplift areas on the ocean surface of the world: northeast Australia, where the uplift area is 76 meters high; The North Atlantic uplift is 68 meters high; In southeast Africa, the uplift area is as high as 48 meters.

(6) There are three major sinking areas in the world ocean: Indian Ocean (south of Indian Peninsula), with sinking depth of112m; Caribbean Sea, with a depression depth of 64 meters; In the west of California, this depression is 56 meters deep. In addition, in the coastal areas of Brazil and the areas near Cape Verde Islands, there are also some areas where the uplift and depression are about15m.

Second, the reasons for the formation of the ocean:

The water in the sea always flows in a regular and clear form, which is called ocean current. One of the most famous is the Gulf Stream, which is 50 miles wide at its narrowest point and has a velocity of 4 kilometers per hour. It goes north along the North American coast, crosses the North Atlantic, and regulates the climate in northern Europe. The North Pacific Ocean current is a similar warm current, which flows from the tropics to the north, raising the temperature on the west coast of North America.

The prevailing wind is the main force to keep the water moving. The different density of seawater is also one of the reasons for ocean currents. The density of cold water is higher than that of warm water, so cold water sinks and warm water rises. Based on the same principle, the cold water near the poles will also sink and flow to the equator below the sea surface. When it reaches the equator, the current rises, replacing the warm water flowing to the poles with surface current.

The coast and mainland of the island also have an influence on the current, either turning the current or dividing it into tributaries. However, in general, the mainstream flows around various ocean basins. Due to the influence of the earth's rotation, the current in the northern hemisphere flows clockwise, while the current in the southern hemisphere flows in the opposite direction.

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