ATMOSPHERIC MOVEMENTS OR WAVES OF THE OCEAN By the atmospheric movements of the ocean, we mean those surface disturbances produced by atmospheric currents or winds acting on the surface of the water. The " waves " thus produced are the simplest of all the movements to which the ocean is subject, and are easily explained. The cohesion of water being limited, its particles obey the slightest impulse ; but water is also all but incompressible, therefore displacement in one place is necessarily accompanied by the occupation of an equal amount of new space—or, in other words, water can never be depressed at one point without being proportionately elevated at another. A current of air moving exactly parallel to the surface of the water does not produce the slightest apparent commotion, but if it strikes the surface, at however small an angle, the water at the point of impact will be more or less depressed, and consequently there will be a correspon ding rise beyond. Thus a " wave " is formed, the elevation or
height above the normal level being exactly equal to the depression below that leveL If the wind continues to blow, similar depressions and elevations are formed in all directions, imparting a kind of undulatory movement to the surface water. These undulations or " waves " increase in magnitude in proportion to the force of the wind and the angle at which it strikes the water. A slight breeze passing over the water, nearly but not quite parallel to the surface, produces small ripples ; but heavy gales or sudden blasts agitate the water violently—the normally-level surface is literally seamed as with vast furrows, frequently 30 to 40 feet from trough to crest.