Surging Underwater World Liu Chen/Wen

The depths of the sea are a dark world, quiet and mysterious, allowing the wind and waves on the surface of the sea to blow and the deep-sea fish to swim leisurely. But calm is temporary, and sometimes the depths of the ocean can be turbulent.

Undersea typhoon

In March 1973, a scientific research vessel arrived in the Sargasso Sea in the western Atlantic Ocean. The ship had a large lineup of scientists from the United States, Great Britain, France and Sweden. In the circular sea of about 200 nautical miles in diameter, scientific expeditions are being carried out intensely. Various deep-sea exploration equipment has been tied into the depths of the ocean, and the sonar detection equipment on board is also working intensely. "What are they doing?" Is it to find sea monsters, or to salvage treasure that has sunk to the bottom of the sea?" Fishermen passing by here speculated.

In fact, this is an ocean dynamic experiment code-named "MODE", and scientists aim to find the large whirlpool in the depths of the sea and study its structural characteristics.

In the late 1950s, the famous oceanographer Stomer pointed out that at a depth of about 2,000-4,000 meters below the North Atlantic Gulf Stream, there was a strong undercurrent flowing southward. In the 1960s, in the study of ocean dynamics, people not only found undercurrents, validated Stommer's theory, but also unexpectedly found that there are large and small whirlpools in the deep sea. These whirlpools are giant swirling columns of water, ranging in diameter from a few meters to hundreds of meters, while heights can extend from the surface of the sea to several kilometers deep on the ocean floor. They rotate rapidly and move forward, a situation similar to the typhoon phenomenon in the atmosphere, so the huge whirlpool is also known as the "undersea typhoon". Of course, they have more formal academic names: oceanographers refer to these vortices as "mesoscale vortices."

"Undersea typhoons" contain enormous amounts of energy, no less than typhoons in the atmosphere on the surface of the ocean. It is estimated that if the diameter of the "submarine typhoon" is 100 meters, its energy is equivalent to that of an offshore typhoon with a diameter of 1000 meters, and the "submarine typhoon" with a movement speed of 10 centimeters per second can be comparable to the sea typhoon that moves 10 meters per second.

So what forces contributed to the formation of this undersea vortex? So far, the mystery of the "undersea typhoon" has not been completely solved. There is a theory that "undersea typhoons" are caused by uneven density of seawater in the ocean. Due to the different energy of sunlight exposure, the temperature of seawater in various parts of the ocean is different, and the salt content is also different, which causes the density of seawater to vary from place to place. Where the density of seawater is high, the relative height of the sea surface is low; where the density of seawater is small, the relative height of the sea surface is high. That is to say, the sea level is not flat, and there are many water peaks and valleys on the surface of the ocean. On the other hand, seawater is a fluid, and the difference in sea level height will cause seawater to flow from a relatively high place to a relatively low place, forming a local area of seawater flow. Affected by the rotation of the Earth, these flowing seawaters change direction, thus forming a rotating whirlpool - "undersea typhoon".

There is also a theory that "undersea typhoons" are formed by currents in the ocean. There are many large seas in the ocean, such as the Gulf Stream, Kuroshio, etc., but these currents do not make a straight line movement, but bend and bend like a snake through the ocean. Under certain conditions, a certain section of the current will bend very badly, and eventually break away from the "big army" and become a closed whirlpool of seawater, rotating while advancing, and further evolving into an "undersea typhoon".

Deep sea waterfalls

There are also waterfalls at the bottom of the sea? yes. There are not only waterfalls in the deep sea, but they are much larger than the waterfalls on the earth's land, and there are deep-sea waterfalls that flow backwards from bottom to top.

(To be continued)