Forget the gentle waves of a sunny day at the beach. The ocean is a terrifying place, capable of displaying fantastical power. Now, a new analysis of the physics behind waves reveals they can reach even more dizzying proportions than was previously believed possible.
Understanding the waves in the world’s largest bodies of water is as important as it is complex. Despite being widely studied, it’s still not entirely clear why waves break the way they do. Yet, waves play an important role in the exchange of gasses between the air and water, which is important information for climate modeling. Being able to forecast enormous rogue waves is also integral to safely designing offshore human-made structures, such as oil and gas rigs, and wind farms. Indeed, knowing just how big ocean waves can get is crucial, and the new study suggests that, according to physical models, these anomalous waves can reach up to four times the height of the highest waves ever recorded.
To get a better grasp of wave dynamics, a group of engineers from the University of Manchester and the University of Oxford took a deep dive into the world of waves. As laid out in their ensuing study, published in Natureit turns out we’ve been thinking about waves all wrong. Water waves were frequently believed to be two-dimensional, moving in a single direction. That, the engineers said, is not entirely accurate, and, under certain specific criteria, waves are capable of moving in multiple directions at once, resulting in gigantic combo waves.
To figure this out, the engineers turned to a unique, circular wave tank located at the FloWave Ocean Energy Research Facility, which allowed them to study waves that weren’t limited in their directional movement. Using a custom-built wave gauge array, they were able to study the structures of the waves as they began to break. Their research built off a previous study, which used the same wave tank to simulate the infamous 1995 Draupner wave. That 84-foot tall (25.6 meters) wave was the first confirmed rogue wave, measuring over twice as big as the average wave in the area in which it occurred.
As they began testing the waters, they simulated the conditions that could occur in a hurricane, where sudden directional changes in powerful winds could end up in waves crossing each other. The more spread out the converging waves were, the larger the combined wave became.
“We show that in these directional conditions, waves can far exceed the commonly assumed upper limit before they break,” said Sam Draycott, a senior lecturer at the University of Manchester, who worked on the study, in a statement. “Unlike unidirectional waves, multidirectional waves can become twice as large before they break.”
It gets even worse. The scientists found that when multiple waves met, they could continue to grow even after breaking. They calculated waves could, in theory, grow four times steeper than was previously thought possible. So, with the largest rogue wave on record at 84 feet, and given the potential for waves to be four times steeper, a quick bit of math suggests the biggest rogue waves could reach 336 feet (102 meters). Yikes. To be clear, this is our extrapolation of the new findings, not an explicit claim made in the paper.
“Once a conventional wave breaks, it forms a white cap, and there is no way back,” said Ton van den Bremer, a researcher from the Netherlands’ Delft University of Technology, who also worked on the study. “But when a wave with a high directional spreading breaks, it can keep growing.”
What still remains to be determined is how all this can play out in the real world. The engineers admitted in the paper they hadn’t taken into consideration how factors like water depth can affect wave height. They also noted that ocean waves are random, while their experiments were highly controlled.
Still, somewhere out there, on a windy day at sea, the physics at play in the lab could result in an absolutely monster rogue wave. With that knowledge now in your brain, try to enjoy your next beach day.
