Waves gently lapping back and forth on the beach, swaying small boats or giving bathers a lot of pleasure with their ups and downs in the water. Strong waves develop such powerful energies that they can even capsize large ships or completely wash away beaches. This phenomenon is one of the most original forces of our nature, which is indispensable from the appearance of picturesque coastal landscapes. But how are waves actually created?
How are waves created?
Pressure differences and vortices of the air
As the wind moves gently over the surface of the water, the water ripples gently. These small waves become stronger – due to air vortices arising in the wave trough and slight air pressure differences in front of or behind the wave crests. After some time, gravity acts on the waves. This makes wave crests steeper and wave troughs rounder.
If gravity exceeds a certain value, the wave crests become unstable and threaten to break. As a result, foam crowns are formed. At the beginning, the wave movements are still relatively slow. However, if the wave motions are faster than the wind speed, they form longer swell waves. In shallow waters, waves get grounded with the bottom. This causes the waves to break because they prevent the circular path of the water so massively that the speed of water particles located in the crest of the wave is higher than the speed of travel of the waves. At short wavelengths and on shallow coasts, the waves break as water moves over the wave fronts. If the waves are longer, the crest of the wave crashes even before the surge. This creates small drop lakes. Particularly dangerous waves are mostly triggered by submarine volcanic eruptions or seaquakes.
Deformed water surface
A wave is a deformed water surface. Individual parts of the water circulate on a circular path, the diameter of which is minimized when the water is deeper. The circular motions are completely eliminated from a depth of half a wavelength. If the deformation continues, the impression is created that a directed water movement is forming on the water.