Back to the Moon with Nuclear Rockets

Shearing suloy on the boundary of the southerly flowing currentof Mozambique Channel, from the Shuttle Discovery,Aug. 16, 1985, at 190 nautical miles.where I feared for the planks," as stated in more than one ofthe log books in Maury's hands.If the chaotic "siomes" in the open ocean extend to depthsof 200 meters, with the degree of turbulence measured byScully-Power from the Kimbla, they possibly represent acousticdiscontinuities as substantial as those in meso-scale eddies.Any knowledge of their generation, distribution, and life historiesis clearly more than academic.Actually, little more is understood about the nature ofchaotic wave-lines than was known in the early 1 980s, otherthan their distribution. Russian oceanographers have done themost work on this strange state of the sea, giving it the name of"suloy." The fullest description of suloys was made by the lateDr. Konstantin Fedorov in his 1983 book on The Physical Natureand Structure of Oceanic Fronts. In it, Fedorov documentsthe regions of the oceans in which suloys are most often encountered,and the variety of ocean conditions under whichsuloys may occur, such as tides, a convergence of currents, atoceanic fronts, or atop internal waves. "Wherever," he notes,"the dynamics of the near-surface ocean cause a convergence,there is a suloy."Tidal suloys are readily explained, because they occur whenstrong tidal currents enter the shallow water of narrow straits.A line of precipitous waves, a suloy, is formed at the front ofthe tidal surge as it meets, and converges with, the surfacewind waves. The precipitous chaotic waves in suloys mayattain heights of 5 m (see photo, p. 41). West of San Francisco'sGolden Gate, waves in the Point Bonita suloy can becomeso intense that even moderate-size ships have requiredmore than one attempt to sail through the roaring wave line.Suloys arise also where the strong discharge from majorrivers converge on waters of the coastal ocean. Such featureshave been observed on several occasions by astronauts inContinued from page 39lands are bright and sharp. In the next instant, they recognizewhitecaps and foam streaks on the sea.Visual observations and photography of whitecaps areclearly not suitable to learn the extent to which theycover the world's sea surface at any given time. Yet, thatknowledge is key to the determination of wind speedsand directions from Earth-orbiting, satellite-bornemicrowave scatterometers. Whitecaps and foam greatlyinfluence the microwave emissivity of the ocean. Themagnitude and variability of this emissivity change is notyet resolved."We continue to observe 'corduroy' and 'herringbone'seas in every part of the ocean where the Sun's glitter givesus a good look at the surface," reported Skylab astronauts,Cols. Gerald Carr and William Pogue, and Dr. Edward Gibson,in January 1974, indicating their ease in observing majorocean swell patterns. The "corduroy" seas are the resultof parallel swell, while the "herringbone" seas are the resultof swell crossing each other at oblique angles.Ocean Swell. When wind waves leave the area of generation,the sea ceases to be random and the dominant waveperiod and direction of propagation take over. The sharppeaks of wind-waves flatten, the height decreases, and aregular pattern of parallel crests appears as the waves aretransformed into swell. As the swell travel onward—throughthousands of kilometers of ocean if no land intervenes—thelongest lengths and greatest periods, predominate. Crestlengths may grow to thousands of meters and become extraordinarilyparallel to each other. These are the corduroyseas visible from space in the great expanses of the oceans(see photo, p. 43, bottom left).Swell from more than one storm-generating region, ororiginating simultaneously from stormy oceans in the Northernand Southern hemispheres, may eventually intersecteach other. In such parts of the ocean, commonly near theEquator, the intersecting swell form the "herringbone seas"that were observed first by the Skylab-4 crew, but subsequentlyon innumerable occasions by astronauts aboard theSpace Shuttle (see photo, p. 43, top right).Breakers, Surf, and Refraction. When a wave approachesthe shore, its crest moves faster than the trough, respondingto the friction exerted by the sea floor. At the moment whenthe velocity of water particles in the crest exceeds the forwardspeed of the wave form, the wave "breaks." The crestovertakes the trough at this stage, the leading slope of thewave becomes steeper than the trailing side, and the top ofthe wave cascades down the steep slope, forming the "surfzone."Waves tend to form "plunging breakers" where bottomslopes to the beach are relatively steep. These are the spectacular"curling" breakers, in which the crests literally collapseonto the steep, forward slope of the breaking wave.Where better to see these crashing giants than at SunsetBeach on the north shore of Oahu in winter? They are theprofessional surfers' joy; the amateurs' continuous "hangten" disasters (see photo, p. 43, bottom right).Continued on page 4542 Summer 1 999 21st CENTURY