The Power of the Waves
Sea waves are among the world’s most misunderstood phenomena. When an incoming wave breaks on the shoreline, it appears as though the water has come to the end of a long journey, but in fact the water itself has hardly moved. Most surface sea waves transmit energy, not water, and the turbulence at the surf zone is the result of that moving energy encountering a solid obstruction—usually the shelving sea floor—against which it noisily dissipates. It is at that point that the wave transforms, from an energy-transporting wave of oscillation to a water-moving wave of translation, more commonly known as “swash.” So for most of its life a wave is not a thing so much as an event, a small part of a largescale transfer of energy from one part of the sea to another.
Waves are most commonly generated by the friction between wind and the surface of the water. As wind blows across the sea, the disturbance and perturbation cause a small wave crest to form, and the resulting up and down motion begins to transmit kinetic energy through the water in the form of a series of waves. As the waves grow, the energy (but not the water) passes from crest to crest, as is apparent when a piece of flotsam, say a tin can, can be seen bobbing up and down on the spot as waves pass beneath it.
Waves are classified according to their wave period or wavelength (the distance between two crests), from the smallest capillary waves to the greatest waves of all, the tides, and those who study them are known as kumatologists, from the Greek (wave), a term coined by the wave-obsessed English geographer Vaughan Cornish in 1899. Capillary waves are the (1867), defined the cat’s paw as “a light air perceived at a distance in a calm, by the impressions made on the surface of the sea, which it sweeps very gently,” and noted the widespread superstition of rubbing a ship’s backstay to invoke the lucky cat’s paw, “the general forerunner of the steadier breeze.” Samuel Taylor Coleridge, en route to Malta in April 1804, wrote a finely observed description of the various wave types seen from deck, starting with the hair’s-breadth ripples of capillary waves:
