AQA AS Geography- The Coastal system - waves

The Coastal System

Waves

• waves are created by the actionof the wind on the sea surface (frictional drag of the wind)

The energy of the wave is determined by:

• Wind velcoity (wind speed)
• Duration: how long the wind blew
• Fetch: the distance over which the wind blew 

Wave motion:

wave motion is limited to one wavelength in the open sea

• Particles within the wave follow a circular orbit (eliptical orbit)
  
• The orbital movement if affected when the water becomes shallower and the rising of the sea floor as the wave gets closer to the coast.

Because the water becomes shallower as the wave approaches the coast, the base of the wave experiences friction with the sea bed however the top of the wave if still moving at full speed; this means that:

• wave height increases
• wave length shortens
• evetually the upper portion of the wave plunges (spills forward)

Constructive and destructive waves:

Constructive waves:

• lower height
• longer wavelength
• lower frequency
• Swash greater that…