After Columbus discovered the New World, exchanges between Europe and the United States became closer and closer, but initially they could only rely on ships to cross the Atlantic Ocean thousands of kilometers wide. In the 1760s, the famous inventor Benjamin Franklin noticed that it took two weeks for postal ships to travel from the United States to England than to return from England to the United States. What happened? After intensive investigation and research, he discovered that there was a strong ocean current flowing from the Americas to the coast of Europe, promoting the rapid navigation of postal ships. This is the Gulf Stream. Later, scientists conducted a more in-depth study of the Gulf Stream, and the results were amazing: "This is a river in the ocean! "
The Gulf Stream is the largest warm current on the earth. It has a total length of about 5000 kilometers, a width of 100 - 150 kilometers, a depth of more than 800 meters, a maximum flow rate of 2.5 meters/second, and a maximum flow rate of 150 million meters ^3/second, which is 120 times the total flow of all rivers in the world. It can be seen how magnificent the momentum of the "river in the ocean" is!
There is also a famous "river" in the Pacific Ocean-the Kuroshio, which flows from the equatorial region to the northeastern coast of Japan in the western Pacific. It is only slightly smaller than the Gulf Stream in scale and is also a powerful warm current.
Why are there "rivers" in the ocean? It turns out that the uneven solar radiation on the earth's surface has caused the planetary wind system to prevail on the ocean surface all year round. For example, the northeastness wind blows on the north side of the equator all year round and the southwest wind blows on the south side, forming an equatorial warm current in the equatorial region, flowing from east to west. When it reaches the west coast of the ocean, it has to turn to high latitudes, including the Gulf Stream and the Kuroshio. These warm currents turn from west to east in the mid-latitudes of the northern and southern hemispheres, gradually transform into cold currents in the process, until the west coast of North America becomes California cold currents, then reaches the east coast of the ocean, and then turns back to the equatorial region. This forms a circulation system. There are many such large-scale circulation in the global oceans, which flow endlessly all year round, transporting energy from the equatorial region to high latitudes in the form of warm currents.
In fact, not only is the surface seawater rushing endlessly, but due to the differences in seawater density in different sea areas, there are also undercurrents in the depths of the ocean. The density of seawater in polar regions and high-evaporation areas such as the Red Sea is high and can sink from the sea surface to the ocean floor and then spread to other areas, creating bottom currents on the seabed. Although this density current flows slowly, it is also an important part of the global ocean current system. This system is extremely complex, just like the arteries and veins in our bodies, transporting matter and energy. Scientists are very concerned about the study of ocean currents because any change in them could have a considerable impact on the global climate.