A week or two ago the topic for Weather Eye was waves, in particular the legendary seventh wave in a rough sea, said to be, very often, very much higher than any of its fellows.
But, oh, what dull and turgid stuff that was compared to accounts of similar phenomena in the book, The Perfect Storm. The breathless prose of Sebastian Junger brings "the random jungle of the sea" dramatically to fearsome life.
He begins, logically enough, at the beginning: "All waves, no matter how huge, start as rough spots - cats' paws - on the surface of the water. The cats' paws are filled with diamond-shaped ripples, called capillary waves, that are weaker than the surface tension of water and die out as soon as the wind stops.
"They give the wind some purchase on an otherwise glassy sea, and at winds over six knots, actual waves start to build. The harder the wind blows, the bigger the waves get and the more wind they are able to `catch'."
Junger goes on to describe how the heights of ocean waves depend on wind strength, on the length of time it blows, and on how much "sea room" is available for waves to grow - "speed, duration, and fetch", as the three parameters are known.
But then he arrives at what he calls the "non-negotiable" wave. "Scientists," he says, "understand how waves work, but not exactly how huge ones work. There are rogue waves out there, in other words, that seem to exceed the forces generating them.
"Typically they are very steep and have an equally steep trough in front of them - a `hole in the ocean' as some witnesses have described it. Ships cannot get their bows up fast enough, and the ensuing wave will break their back." According to Junger, the biggest rogue wave on record was that experienced in a Pacific gale by the tanker Ramapo in 1933. "Early on the morning of February 7th the watch officer glanced to stern and saw a freak wave rising up behind him that lined up perfectly with a crow's nest above and behind the bridge. Simple geometry later showed the wave to be 112 feet high."
And finally he gives an entirely different version of the legend of the seventh wave: "Rogue waves are thought to be several ordinary waves that happen to get `in step', forming highly unstable piles of water. Others are waves that overlay long-distance swells from earlier storms.
"Such accumulations of energy can travel in threes - a phenomenon called `the three sisters' - and are so huge they can be tracked by radar."