1. Wave phenomena transmit energy through various states of matter by setting up patterns of oscillatory motion in the particles that make up the matter.
2. Most of the waves observed at sea are progressive wind waves, i.e., they are generated by winds. The distance over water, where the wind blows in a single direction is called as fetch.
3. Progressive waves are longitudinal, transverse, or orbital depending on the pattern of particle oscillation. Particles in ocean waves move primarily in orbital paths.
4. Characteristics used to describe waves are wave length (L), wave height (H), wave period (T), and wave speed (S).
image source: image source: bgfons.com/upload/waves_texture2428.jpg
ADVERTISEMENTS:
5. If water depth is greater than 14 wavelengths, a progressive wave travels as a deep-water wave with a speed that is directly proportional to wavelength.
6. If water depth is less than 1/20 wavelength, the wave will move as a shallow-water wave, the speed of which increases with increased water depth.
7. As wind-generated waves form in a sea area, capillary waves with rounded crests and wavelength less than 1.74 centimeters (0.7 inches) form first. As the energy of the waves increases, gravity waves form, with increased wave speed, wavelength, and wave height.
ADVERTISEMENTS:
8. Energy is transmitted from the sea area across the ocean by low, rounded waves called swell. Because swellsjnay move away from a number of storm areas in any ocean, it is inevitable that the swell from different storms will run together and the waves will clash or interfere with one another.
This gives rise to a special feature of wave motion interference pattern. An interference pattern is produced when two or more wave systems collide. This interference pattern is the algebraic sum of the disturbance that each wave would have produced individually.
The result may be a larger or smaller trough or crest depending on conditions. Thus, there are two types of interferences constructive and destructive.
Constructive interference occurs whenever and wherever a number of wave crests or troughs coincide and combine to produce a composite wave that is much larger than any of the individual wave components.
ADVERTISEMENTS:
When there is extraordinary constructive wave interference, a wave of unusually large size for the prevailing wind conditions is created. This is called rogue Waves.
9. Swell releases its energy in the surf as waves that break in the shoaling water near shore. If waves break on a relatively flat surface, the result is usually a spilling breaker, whereas breakers forming on steep slopes have spectacular curling crests and are called plunging breakers. Others types of breakers are spilling, surging and collapsing.
10. The piace where the waves constantly and continuously break the water becomes foamy. This is called as surf zone after breaking some of the water moves towards the shore. This is called swash. The water that moves away from the shore into the sea at the bottom is called as backwash.
11. When swash is more powerful than backwash it builds and consequently is called constructive wave. When backwash is more powerful than swash it is called destructive waves.
12. Reflection of waves off seawalls or other barriers can cause an interference pattern called a standing wave. In standing waves, crests do not move laterally as in progressive waves but form alternately with troughs at locations called antinodes. Separating the antinodes are nodes, where there is no vertical movement of the water.
13. During storms, the combination of low air pressure and onshore winds may produce a storm surge that raises the water level at the shore many metres above normal sea level. Such surges are particularly destructive if they coincide with high tide.
14. Tsunamis, or seismic sea waves, are generated by seismic disturbances beneath the ocean floor. Tsunamis have been known to cause large scale damage and take tens of thousands of lives.
15. Internal waves are not well understood but are thought to form at density interfaces beneath the ocean surface, especially in connection with the pycnocline. They may be up to 100 metres (330 feet) high, with periods from 5 to 8 minutes.
16. Some waves that do not move horizontally but remain stationary are called Seiches. Such waves oscillate around a fixed point called a node.