Question

How do waves change as they approach the shore?

Answer 1

Hint: Ocean water movements are classified into various categories like ocean currents and waves for horizontal movement and tides for vertical movements. Waves are generated by wind energy on the surface of the ocean that gives rise to small circular movements of the water. The wind carries the waves all the way to the shorelines where they break and dissolve as surf. Steeper waves are formed due to local winds and are fairly young while slow and steady waves originate at a farther distance and travel longer.

Complete answer:Two energies affect a wave: the wind which pushes the water body in its course and the gravity of the earth which pulls the crests (rising part of the wave) downwards. As the wave approaches the shore, it slows down because of the friction that occurs between the water and the seafloor, now that the depth of water has decreased. The wave breaks when the depth of the water is half the wavelength of the wave. Although the initial movement of the wave is up and down, at the shore, the dominant movement becomes the back and forth thus resulting in a swash followed by backwash.

Note: The highest point of a wave is called the crest and the lowest point is called the trough. The vertical distance between the bottom of the trough and the top of the crest can be described as the wave height whereas, the horizontal distance between two subsequent crests is called the wavelength.