The beautiful ocean has attracted countless surfers and divers to spend time, energy and money, risking their lives to explore the beautiful experience brought by the ocean to mankind.
However, under the beautiful and gentle mother-like face of the ocean, there is also a frightening ocean danger brought by its huge volume. 20 1 1 Japan's tsunami was very powerful, and at the same time it caused a serious secondary disaster of nuclear power plant leakage.
The terror of the sea is not only reflected in the huge marine life, but also in many peculiar marine phenomena that make the navigators avoid, just like the mythical song of Sai Ren. Once caught, it will be a narrow escape.
What is rip current? What is mad dog wave? What is eddy current? What are the reasons for these phenomena? Next, this paper will introduce the real ocean from several strange and frightening marine disasters: tearing current, crazy dog wave, eddy current and tsunami.
On March 20 10, on the way from Spain to Italy, a strong wind suddenly blew at sea. Three hours later, a huge wave as high as 8 meters rushed to the cruise ship, and the second and third waves followed. The waves broke the ship's glass, and two tourists died on the spot, and more than a dozen tourists were injured. Then the wave disappeared without a trace.
This is the mad dog wave, which is powerful without warning, and because of its "quick victory" attribute, it has been regarded as a legend until it is really discovered.
19 17, after a series of rigorous calculations, American oceanographer Walter Monk was surprised to find that the waves on the beach on the west coast of Mexico actually originated in Antarctica, which is 14500 kilometers away. Later, his team collected data all over the world and revealed the formation mechanism of mad dog wave.
When there is a storm on the sea, the sea will absorb energy. When the storm is over, the sea surface will be calm, but the energy will make the sea surface form waves and make the sea water move for a period of time after the storm. This kind of wave is crazy dog wave, also called surge. Surge travels far, fast and powerful.
In the past, it was thought that in the process of wave propagation, if waves in different directions were encountered, the forces of the two waves would cancel out and dissipate, but this is not the case. When they cross, they will not lose energy due to collision, which also leads to mad dog waves can spread nearly half the world and still have great power.
The name "rip current" sounds harmless, but don't underestimate it. It is a fast-moving ocean current formed in the wave breaking area near the beach, moving away from the coast perpendicular to the coastline. People who have not received professional training, once involved in the tearing stream, will be taken from the beach to the sea, but there is nothing they can do, and will eventually drown because of exhaustion of physical strength.
Rip current, also known as "rip current", is confusing to some extent. Before it happened, the sea was relatively calm. Once it happens, it usually lasts for a few minutes to tens of minutes, with an average speed of 0.5 ~ 2m/s. If there is a tearing flow of 2m/s, only Olympic champions can draw with it. Every year, 100 committees in the world die due to tearing current.
The formation of crevasse is closely related to the wind, which will bring waves and the waves will spread along the water surface. When reaching the shallow water area, the waves will break into white waves due to the increase of friction on the seabed, which is also the highest point of the waves. It is less likely that there will be fissures on the gentle coast, but the probability of fissures will be greatly increased if there are trenches and other uneven terrain near the coast.
Because of the large kinetic energy, the waves that hit the coast from the ocean can easily pass through the trench and hit the coast, while the returning waves cannot return to the ocean from the trench because of the low speed, resulting in excessive water accumulation in the trench. Once the critical value is reached, the seawater in the trench will rush into the ocean from the lower gap of the trench, and then a fissure will occur.
At present, rip current is unpredictable. If we want to enjoy surfing and minimize the risk, we need to do the following three things before surfing: strictly abide by the rules of beach play, choose a regular beach and keep ourselves in the sight of lifeguards. Learn to identify fissure water, which will become darker because it carries a lot of sediment, and breaking waves is also one of the obvious signs. Once you are caught in the rapids, you should keep calm.
Rip current generally doesn't drag people down. Take a deep breath to float your body. If we have the strength, we can choose to swim parallel to the waves and try to drift away from the tearing flow area.
As we all know, the ocean vortex is powerful. A vortex near the coast of Sydney actually lowered the nearby sea level 1 m when it was spinning. In the era when there were no satellites, eddy currents were extremely hidden. Standing on the coastline, you can't observe the sea level drop caused by the vortex, and you can't find any clues from the sky until the satellite appears.
Sartre vortex is one of the largest eddies on the earth. It is located in Norway in the Arctic Circle, and its current slowness is related to the moon's surplus and deficiency. The current is strongest when the moon is full and slower when the moon is hooked, which also casts a romantic atmosphere on this vortex. In the middle of the month, the Sartre vortex was very dangerous, and ships of all sizes were not allowed to pass, and many fishermen died here.
There are different opinions about the causes of eddy current. Some people think that the excessive curvature of ocean currents causes some ocean currents to leave the mother body and form eddy currents. Others believe that it is caused by the gravity of the sun and the moon. Solar radiation is the main source of all energy on the earth. When the sun and the moon are at the same end of the earth, gravity will make the sea water flow in one direction, and the earth will rotate to form a vortex. At present, scientists are trying to combine mathematics, physics, meteorology and geology to create a mathematical model to predict ocean behavior.
Although we always subconsciously associate vortex with danger when we hear it, another advantage of vortex is that it can wash nutrients accumulated in deep sea into shallow water and provide energy for plankton.
20 1 1 year, the tsunami triggered by Japan's M8.8 earthquake set off waves nearly ten meters high in Sendai and Xingang, causing tens of thousands of deaths. If the tsunami is not in the highlands, the chances of survival are relatively low. In such a fierce wave, even the swimmers were taken away. Moreover, if the tsunami happens around the city, people will easily lose their resistance directly when they are hit by the waves, and at the same time, they may choke the seawater and be directly poured into their stomachs by the sediment.
65438+8: 58 On February 26th, 2004, a 9.3-magnitude earthquake struck the seabed 30km north of Sumatra Island, Indonesia, killing 290,000 people and injuring 5 1 10,000 people. Somalia, 5000 kilometers away from the earthquake center, was also hit by a tsunami as high as 9 meters, killing hundreds of people.
The speed of tsunami propagation is related to the depth of the seabed. The deeper the seabed, the faster the tsunami travels. When the tsunami approaches the shore, the depth decreases, the wave velocity slows down, and the subsequent wave velocity becomes faster, resulting in the larger the seawater volume and the higher the wave height.
Submarine earthquake is one of the main causes of tsunami, and basically three-quarters of tsunami is caused by submarine earthquake. For example, the Japanese tsunami of 20 1 1; 5% of tsunamis are caused by submarine volcanic eruptions, such as the Indonesian tsunami mentioned above.
China also has a long coastline. At present, there is no earthquake or tsunami in Bohai Sea. However, we also need to establish a more perfect marine early warning mechanism to protect the life safety of our citizens, and at the same time, we must maintain awe of nature and not blindly swim in deep water areas, so as to better protect our personal safety.