There is an abundance of water inundating large swathes of planet Earth. As wind and vibrations play upon it, waves within the liquid medium are produced, sometimes barely a ripple, and sometimes a 90-foot giant. There are two types of waves—“wind waves,” generated by wind blowing across the surface of the water, and “tsunamis,” which are waves generated by geologic incidences such as earthquakes. The structure of a wave consists of a crest, its maximum height and a trough, its maximum depth. Scientists studying waves are most concerned with the wave height, which is the measurement from the trough to the crest, the wavelength, which is the measurement from crest to crest, the period, which is the interval of time that crests arrive at a fixed point, and finally, wave propagation, or the general direction the wave is traveling. But just as physics dictates a wave’s creation, inevitably, the wave will cease to exist. The most visible instance of this is when water reaches a shoreline. There it may break wherein the crest of the wave collapses onto itself. A spilling wave is a slowly breaking wave on a gradually sloping shoreline, but on steeper shorelines, the waves may plunge, breaking suddenly, or surge, not break at all. But throwing a wrench into this system is the dreaded rogue wave. Mostly seen in the deep ocean, where normal waves can reach heights of 49 feet, this monster wave can grow to twice that and strike without warning. The phenomenon is not fully understood yet. Some theories assert that shoreline or seabed shapes cause the coalescing of a single large wave from many small waves, or that a rogue wave is created by a “sucking” of energy from surrounding waves, or that storm winds and ocean currents can collide to form a rogue wave at the point of collision. Scientists are studying this situation closely, assisted by the European Space Agency’s ERS satellites, which are taking a rogue wave “census” using radar.
Photo: Jim Krajicek