Dishonest waves are more than legends – one was recreated in Scotland



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The Great Wave of Kanagawa, an artistic representation of what is possibly a dishonest wave.Katsushika Hokusai; Wikimedia Commons / Public Domain

If you think a "cheating wave" sounds like oceanographic damage, then you would be right: according to the National Oceanic and Atmospheric Administration (NOAA), evil waves are "big, unexpected and dangerous."Noting that they have been a part of maritime folklore for some time, they add that only lately they have been considered serious scientific phenomena. The problem is that their training mechanisms are very poorly understood.

Technically, wandering waves are those that are twice the height of the surrounding waves, appear almost out of nowhere and emerge from directions other than wind and prevailing waves. Other than that, they are very ambiguous things, partly because their documented appearances are so rare that they are incredibly difficult to study. This is very inconvenient considering they can sink boats and cause some confusion.

One, if not The invasive first wave to be officially detected by scientific equipment and duly quantified was the Draupner Wave, which hit the Norwegian oil platform of the same name in the North Sea on New Year's Day in 1995. Although it did not destroy the platform nor caused any major damage, it reached 26 meters (84 feet) in height as recorded by the sensors at laser on the platform at the moment.

Although this arguably pushed dishonest waves from the anecdotal to the scientific realm, not much could be done with the recorded wave height data. It simply did not force the field, particularly when it came to training mechanisms – until, of course, a team led by Oxford University took a rather clever approach to the process.

One way of trying to figure out how large-scale things form is to recreate the conditions in a laboratory environment. I actually did this for my own doctoral thesis, which involved imitating certain volcanic explosions in a laboratory. That, incidentally, was as deliciously confused as it sounds. Researchers do this all the time, from how diamond superdeep are created to simulate the giant impact who formed the Moon (and perhaps sowed the Earth with the chemical ingredients for life). It does not explain everything conclusively, but it allows scientists to see processes running on a scale that we can pause, rewind, move forward and customize in any other way.

Waves are also frequent subjects of laboratory replication. The record of 524 meters (1,719 feet) in height megatsunami in the Bay of Lituya, Alaska, in July 1958, was thought to have been formed by a single massive landslide in the water for several decades. However, laboratory experiments in recent years have suggested that it was caused by two very close landslides, which (among other things) helped to create a trapped air bag that helped push so much water forward.

And so it goes to the Draupner wave. The team of independent engineers and scientists, using what is essentially a pool with various wave generation mechanisms, tried to recreate it and thus discover how it formed in the first place.

Generally speaking, there are two ideas at stake about how dishonest or "weird" waves can form. If you remember your high school physics classes, you may remember that waves can interfere with each other, because when the waveforms intersect, they may be in sync and amplify each other or may be out of and weaken each other. The first, known as constructive interference, is perhaps one of the reasons why malignant waves take shape.

Another possibility is that waves, forged by a storm, may find their frequencies shortened as they press against the flow of a preexisting wave direction. This can put several waves in tune with each other, uniting them and forming a dishonest wave of longer life.

That's all conjecture when it comes to soggy reality, however, the team hoped to find out precisely what was happening when the Draupner wave made its debut. Writing on Journal of Fluid Mechanics, the team found that when two waves intersect at considerable angles – around 120 degrees, in fact – they seem to turn into a much bigger wave.

As noted by ArsTechnica, this is not the first time a dishonest wave has been created in a laboratory environment. Some early attempts have used tanks and oars of linear waves, and have found that all that is needed is a little disturbance; one wave gets a bit higher than the others, the waves behind slow down and accumulate, increase, and a feedback loop ensures that a large wave is formed.

It's fair, but the sea is not linear, and the waves do not usually form when the blades splash water. These races also do not inform scientists about the role of wave breaking, which is when the crest of a steep wave falls in front of the rest of the wave, slowing it down, flattening or disintegrating. Wave breaking is considered a limiting factor in the ability to form cheating waves.

As an earlier experimental setup used by the University of Turin, the University of Edinburgh pool FloWave Ocean Power Search Facility has a circular tank to better simulate the open sea. This allows waves to cross at different angles, as would naturally occur. The team noted that at large angles, not only do the two waves join forces to produce a larger one, but the wavelength no longer limits the height of a wave. Both explain how a wave can form, including the Draupner wave, whose infant equivalent was replicated successfully in the pool.

Although some assumptions about the wave dynamics present on that day in 1995 had to be understandably made, this study is still a really clear way of explaining how a very puzzling oceanographic curiosity may appear. It also elucidates clearly why malignant waves are rare: to make two waves of this kind cross that angle simply can not happen very often.

It is not mentioned in the study, but the Press release accompanying references The Great Wave of Kanagawa, a famous wooden block painted in the early 19º Century by Japanese artist Katsushika Hokusai. You've probably seen it somewhere before without even knowing its origin.

The researchers certainly had: they noticed that their laboratory wave had a morphological similarity to the print itself, which shows several fishing boats being consumed by the sea. It is not easy to say how much creative license Hokusai put in its representation of this specific wave, but it is remarkable that some thought this would represent a tsunami of some sort. It makes more sense, however, that it is showing a dishonest wave.

Clearly, we are fascinated by these aquatic monsters largely unexplained for centuries – and this latest study leads us to understand them in new and exciting ways.

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The Great Wave of Kanagawa, an artistic representation of what is possibly a dishonest wave.Katsushika Hokusai; Wikimedia Commons / Public Domain

If you think a "dishonest wave" sounds like oceanographic damage, then you would be right: according to the National Oceanic and Atmospheric Administration (NOAA), evil waves are "big, unexpected, and dangerous." Noting that they have been part of maritime folklore for some time, they add that they have only recently been considered serious scientific phenomena. The problem is that their training mechanisms are very poorly understood.

Technically, wandering waves are those that are twice the height of the surrounding waves, appear almost out of nowhere and emerge from directions other than wind and prevailing waves. Other than that, they are very ambiguous things, partly because their documented appearances are so rare that they are incredibly difficult to study. This is very inconvenient considering they can sink boats and cause some confusion.

One, if not The the first dangerous wave to be officially detected by scientific equipment and duly quantified was the Draupner wave, which hit the Norwegian oil platform of the same name in the North Sea on New Year's Day in 1995. Although it did not destroy the platform or cause any damage larger, it reached a considerable height of 26 meters (84 feet) in height, as recorded by the laser sensors on the probe at the time.

Although this arguably pushed dishonest waves from the anecdotal to the scientific realm, not much could be done with the recorded wave height data. It simply did not force the field, particularly when it came to training mechanisms – until, of course, a team led by Oxford University took a rather clever approach to the process.

One way of trying to figure out how large-scale things form is to recreate the conditions in a laboratory environment. I actually did this for my own doctoral thesis, which involved imitating certain volcanic explosions in a laboratory. That, incidentally, was as deliciously confused as it sounds. Researchers do this all the time, from designing how diamonds superdeepes are created to simulate the giant impact that formed the Moon (and perhaps sow the Earth with the chemical ingredients for life). It does not explain everything conclusively, but it allows scientists to see processes running on a scale that we can pause, rewind, move forward and customize in any other way.

Waves are also frequent subjects of laboratory replication. The 524-meter megatsunami record in Lituya Bay, Alaska, in July 1958, would have been made up of a single enormous landslide in the water for several decades. However, laboratory experiments in recent years have suggested that it was caused by two very close landslides, which (among other things) helped to create a trapped air bag that helped push so much water forward.

And so it goes to the Draupner wave. The team of independent engineers and scientists, using what is essentially a pool with various wave generation mechanisms, tried to recreate it and thus discover how it formed in the first place.

Generally speaking, there are two ideas at stake about how dishonest or "weird" waves can form. If you remember your high school physics classes, you may remember that waves can interfere with each other, because when the waveforms intersect, they may be in sync and amplify each other or may be out of and weaken each other. The first, known as constructive interference, is perhaps one of the reasons why malignant waves take shape.

Another possibility is that waves, forged by a storm, may find their frequencies shortened as they press against the flow of a preexisting wave direction. This can put several waves in tune with each other, uniting them and forming a dishonest wave of longer life.

That's all conjecture when it comes to soggy reality, however, the team hoped to find out precisely what was happening when the Draupner wave made its debut. Writing in the Journal of Fluid Mechanics, the team discovered that when two waves intersect at fairly large angles – about 120 degrees, in fact – they seem to turn into a much larger wave.

As noted by ArsTechnica, this is not the first time that a dishonest wave is created in the laboratory. Some early attempts have used tanks and oars of linear waves, and have found that all that is needed is a little disturbance; one wave gets a bit higher than the others, the waves behind slow down and accumulate, increase, and a feedback loop ensures that a large wave is formed.

It's fair, but the sea is not linear, and the waves do not usually form when the blades splash water. These races also do not inform scientists about the role of wave breaking, which is when the crest of a steep wave falls in front of the rest of the wave, slowing it down, flattening or disintegrating. Wave breaking is considered a limiting factor in the ability to form cheating waves.

As an earlier experimental facility used by the University of Turin, the FloWave Oceans Energy Research Center at the University of Edinburgh features a circular tank to better simulate the open sea. This allows waves to cross at different angles, as would naturally occur. The team noted that at large angles, not only do the two waves come together to produce a larger one, but the wavelength does not limit the height of a wave anymore. Both explain how a wave can form, including the Draupner wave, whose infant equivalent was replicated successfully in the pool.

Although some assumptions about the wave dynamics present on that day in 1995 had to be understandably made, this study is still a really clear way of explaining how a very puzzling oceanographic curiosity may appear. It also elucidates clearly why malignant waves are rare: to make two waves of this kind cross that angle simply can not happen very often.

It is not mentioned in the study, but the accompanying press release makes reference The Great Wave of Kanagawa, a famous wooden block painted in the early 19º Century by Japanese artist Katsushika Hokusai. You've probably seen it somewhere before without even knowing its origin.

The researchers certainly had: they noticed that their laboratory wave had a morphological similarity to the print itself, which shows several fishing boats being consumed by the sea. It is not easy to say how much creative license Hokusai has put in its representation of this particular wave, but it is remarkable that some think it depicts a tsunami of some sort. It makes more sense, however, that it is showing a dishonest wave.

Clearly, we are fascinated by these aquatic monsters largely unexplained for centuries – and this latest study leads us to understand them in new and exciting ways.

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