Ghost Wave - Chris Dixon [52]
As earlier scientists theorized, there comes a moment during the evolution of a storm when gravity asserts its dominance over a swell. It is simply carrying so much water that its weight prevents it from growing any higher. At this point, the sea state is said to be fully developed. In modern theory (that is, what is generally accepted today), the maximum height for a fully developed, single open-ocean swell is 78 feet high with a period of twenty-three seconds and a velocity of seventy-seven miles an hour. This occurs after a seventy-knot wind has been pushing on the swell for a thousand or so miles.
However, the Ramapo was in just this situation, and it would soon record a single rogue wave nearly 50 percent higher still. How can this be?
Simply put, this tidy calculation of potential wave height is insufficient to account for the almost incomprehensibly complex physics of wave generation, and science has come to accept that what appears to be a single wave is, in some cases, anything but. So while open-ocean waves should fit this formula, exceptions occur all the time and for a whole host of reasons. Not only do waves interact with the swirling atmosphere and respond rapidly to changes in wind speed, but because waves of different periods run at different speeds, they regularly run through and over their brethren. One wave might cancel out or highly amplify the energy of another, a process scientists call nonlinear transfer. A 30-foot, 10-second wave 100 feet deep might be overtaken by a 60-foot marauder 20 seconds long and 1,200 feet deep; this might result for a short time in a single 90-footer we call a “rogue wave.” Or a line of big swells might crash headlong into a strong ocean current like the Gulf Stream—and stack up like a chain-reaction crash on a freeway into a series of steep, deadly peaks. The result is a temporary but highly unstable wave, actually a trio of rogues, that mariners call “The Three Sisters.” These climb far higher—perhaps even two to three times higher than the surrounding swells—and their troughs can seem so fathomless that they have been called “holes in the ocean.” When one wave runs over the top of another, it can actually rise up and shoal across the slower wave’s back, producing a gigantic breaker that, like the Cortes Bank, appears in the empty open ocean. These waves are not uncommon at all. A famous 2001 European Union study called “Max Wave” used a network of global satellites to determine that, at any single point in time, there are probably eight or nine such rogue waves—either in single or “three sisters” form—coursing through the world’s oceans.
In his article, Whitemarsh describes several similar encounters then known to mariners of his day. In 1837, Jules Dumont d’Urville claimed to have seen a 100-foot wave while sailing around the Cape of Good Hope. In 1861, a 100-foot-high lighthouse off England’s Isles of Scilly was struck by a wave that tore off the bell in her tower. The Tillamook Light in Oregon had seen days when waves blasted rocks through windows 133 feet high.
Even Christopher Columbus told of giant, seemingly impossible waves during his third trip to the New World in 1498. Columbus was leading a fleet of six ships through a stormy, narrow passage at the southern tip of Trinidad. He heard “a fearsome roaring” and turned to see a wave higher than his over-60-foot masts bearing down on the flotilla. It lifted all the ships higher than anything the admiral had ever seen and then dropped them into a frightening trough, burying them with foam and spray. He named the passageway “The Mouth of the Serpent.”
The passengers aboard the Annie Jane were