wave

—waveless, adj. —wavelessly, adv. —wavingly, adv. —wavelike, adj.

/wayv/, n., v., waved, waving.

n.

1. a disturbance on the surface of a liquid body, as the sea or a lake, in the form of a moving ridge or swell.

2. any surging or progressing movement or part resembling a wave of the sea: a wave of the pulse.

3. a swell, surge, or rush, as of feeling or of a certain condition: a wave of disgust sweeping over a person; a wave of cholera throughout the country.

4. a widespread feeling, opinion, tendency, etc.: a wave of anti-intellectualism; the new wave of installment buying.

5. a mass movement, as of troops, settlers, or migrating birds.

6. an outward curve, or one of a series of such curves, in a surface or line; undulation.

7. an act or instance of waving.

8. a fluttering sign or signal made with the hand, a flag, etc.: a farewell wave.

9. natural waviness of the hair, or a special treatment to impart waviness: to have a wave in one's hair; to get a shampoo and a wave.

10. a period or spell of unusually hot or cold weather.

11. Physics. a progressive disturbance propagated from point to point in a medium or space without progress or advance by the points themselves, as in the transmission of sound or light.

12. Literary.

a. water.

b. a body of water.

c. the sea.

13. (at sports events, esp. baseball games) a momentary standing and sitting back down by spectators in a sequential, lateral way to create, en masse, a wavelike effect visually.

14. make waves, Informal. to disturb the status quo; cause trouble, as by questioning or resisting the accepted rules, procedures, etc.: The best way to stay out of trouble at the office is not to make waves.

v.i.

15. to move freely and gently back and forth or up and down, as by the action of air currents, sea swells, etc.: The flags were waving in the wind.

16. to curve alternately in opposite directions; have an undulating form: The road waved along the valley.

17. to bend or sway up and down or to and fro, as branches or plants in the wind.

18. to be moved, esp. alternately in opposite directions: The woman's handkerchief waved in encouragement.

19. to give a signal by fluttering or flapping something: She waved to me with her hand.

v.t.

20. to cause to flutter or have a waving motion in: A night wind waves the tattered banners.

21. to cause to bend or sway up and down or to and fro: The storm waved the heavy branches of the elm.

22. to give an undulating form to; cause to curve up and down or in and out.

23. to give a wavy appearance or pattern to, as silk.

24. to impart a wave to (the hair).

25. to move, esp. alternately in opposite directions: to wave the hand.

26. to signal to by waving a flag or the like; direct by a waving movement: to wave a train to a halt; to wave traffic around an obstacle.

27. to signify or express by a waving movement: to wave a last good-bye.

[1325-75; ME waven (v.), OE wafian to wave the hands; c. MHG waben; cf. WAVER¹]

Syn. 1. undulation, whitecap. WAVE, RIPPLE, BREAKER, SURF refer to a ridge or swell on the surface of water. WAVE is the general word: waves in a high wind. A RIPPLE is the smallest kind of wave, such as is caused by a stone thrown into a pool: ripples in a brook. A BREAKER is a wave breaking, or about to break, upon the shore or upon rocks: the roar of breakers. SURF is the collective name for breakers: Heavy surf makes bathing dangerous. 15. undulate, flutter, float, sway, rock; fluctuate.

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I

In oceanography, a ridge or swell on the surface of a body of water, normally having a forward motion distinct from the motions of the particles that compose it.

Ocean waves are fairly regular, with an identifiable wavelength between adjacent crests and with a definite frequency of oscillation. Waves result when a generating force (usually the wind) displaces surface water and a restoring force returns it to its undisturbed position. Surface tension alone is the restoring force for small waves. For large waves, gravity is more important.

II

Propagation of disturbances from place to place in a regular and organized way.

Most familiar are surface waves that travel on water, but sound, light, and the motion of subatomic particles all exhibit wavelike properties. In the simplest waves, the disturbance oscillates periodically (see periodic motion) with a fixed frequency and wavelength. Mechanical waves, such as sound, require a medium through which to travel, while electromagnetic waves (see electromagnetic radiation) do not require a medium and can be propagated through a vacuum. Propagation of a wave through a medium depends on the medium's properties. See also seismic wave.

III

(as used in expressions)

tidal wave

seismic sea wave

New Wave

radio wave

seismic wave

wave front

wave function

wave cut platform

wave particle duality

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▪ water

 on a body of water, a ridge or swell on the surface, normally having a forward motion distinct from the oscillatory motion of the particles that successively compose it. The undulations and oscillations may be chaotic and random, or they may be regular, with an identifiable wavelength between adjacent crests and with a definite frequency of oscillation. In the latter case, the waves may be progressive, in which the crests and troughs appear to travel at a steady speed in a direction at right angles to themselves. Alternatively, they may be standing waves (standing wave), in which there is no progression. In this case, there is no rise and fall at all in some places, the nodes, while elsewhere the surface rises to a crest and then falls to a trough at a regular frequency.

      A brief treatment of water waves follows. For full treatment, see ocean: Waves of the sea (ocean).

      There are two physical mechanisms that control and maintain wave motion. For most waves, gravity is the restoring force that causes any displacements of the surface to be accelerated back toward the mean surface level. The kinetic energy gained by the fluid returning to its rest position causes it to overshoot, resulting in the oscillating wave motion. In the case of very short wavelength disturbances of the surface, i.e., ripples, the restoring force is surface tension, wherein the surface acts like a stretched membrane. If the wavelength is less than a few millimetres, surface tension dominates the motion, which is described as a capillary wave. Surface gravity waves in which gravity is the dominant force have wavelengths greater than approximately 10 cm (4 in.). In the intermediate length range, both restoring mechanisms are important.

      The mathematical theory of water wave propagation shows that for waves whose amplitude is small compared to their length, the wave profile can be sinusoidal, and there is a definite relationship between the wavelength and the wave period, which also controls the speed of wave propagation. Longer waves travel faster than shorter ones, a phenomenon known as dispersion. If the water depth is less than one-twentieth of the wavelength, the waves are known as long gravity waves, and their wavelength is directly proportional to their period. The deeper the water, the faster they travel. For capillary waves, shorter wavelengths travel faster than longer ones.

      The energy of the waves is proportional to the square of the amplitude, i.e., the maximum displacement of the surface above or below its rest position. Mathematical analysis shows that a distinction must be made between the speed of the troughs and crests, called the phase speed, and the speed and direction of the transport of energy or information associated with the wave, termed the group velocity. For non-dispersive long waves the two are equal, whereas for surface gravity waves in deep water the group velocity is only half the phase speed. Thus, in a train of waves spreading out over a pond after a sudden disturbance at a point, the wave front travels at only half the speed of the crests, which appear to run through the packet of waves and disappear at the front. For capillary waves, the group velocity is one and one-half times the phase speed.

      Waves whose amplitude is large compared to their length cannot be so readily described by mathematical theory, and their form is distorted from a sinusoidal shape. The troughs tend to flatten and the crests sharpen toward a point, a shape known as a conoidal wave. In deeper water the limiting height of a wave is one-seventh of its length. As it approaches this height the pointed crests break to form whitecaps. In shallow water the long-amplitude waves distort, because crests travel faster than troughs to form a profile with a steep rise and slow fall. As such waves travel into shallower water on a beach, they steepen until breaking occurs.

      Waves on the sea surface are generated by the action of the wind. During generation the disturbed sea surface is not regular and contains many different oscillatory motions at different frequencies. Wave spectra are used by oceanographers to describe the distribution of energy at different frequencies. The form of the spectrum can be related to wind speed and direction and the duration of the storm and the fetch (or distance upwind) over which it has blown, and this information is used for wave prediction. After the storm has passed, the waves disperse, the longer-period waves (about 8 to 20 seconds) propagating long distances as well, while the shorter-period waves are damped out by internal friction.

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