What changes occur in a wave as it approcaches shore?

Question

waves and tides

Answer 1

Waves always travel towards the shore,no matter which way the wind blows.But,out at sea(ie in the midst of oceans or seas),waves tend to travel in the same direction as the wind is blowing.

Diffraction and refraction are the two factors which cause the waves that approach a coast to move always towards the shore(ie., parallel to shore).

Diffraction causes waves to spread out after they pass through a gap such as entrance to a harbour or an enclosed bay causing the waves to head towards all sides of the harbour.

Refraction occurs when the waves travel into changed conditions such as the shallow water that is found near a shoreline.This is because,as the waves enter the shallow water,they change direction(or refract),slow down and realign such that they travel towards the shore.

Answer 2

the oscillations associated with sea waves are principally generated by winds, though tides and seismic movements also have an effect. the water movements are both longitudinal and transverse. the basic behaviour is for the particles of water to move in circles in a vertical plane containing the direction of propagation. the motion decreases with increasing depth below the water surface. the wave velocity, which depends on wavelength is also affected by the depth of water, being slower in shallow water than it is in deep water. for this reason waves tend to turn inwards as they approach the shore. under these conditions,attenuation can become so marked that the waves 'break' and there is then a bodily movement of water in the direction of propagation of the wave.