SOUTHERLY WESTERLY 



SOUTHERLY WESTERLY NORTHERLY 



TRACK 



MAP VIEW 



TIME SERIES 



Figure 1 . Changes in barometric pressure, wind speed, wind direction, 

 wave heigiit, wave period, and surge as a cyclone passes 

 laterally offshore along a north- and south-facing coastline in 

 the Northern Hemisphere (adapted from Carter 1988) 



Waves 



Waves are of great importance in the formation and variability of coastal 

 geomorphic features. They are especially effective in the shore and shoreface 

 areas, where they are capable of moving sediment directly or by generation of 

 longshore currents. Wind waves, the most common type, are generated by 

 wind stress on the water surface. The height and energy of wind waves 

 increase with increasing wind velocity, fetch (the extent of water over which 

 the wind blows), and wind duration. 



Waves impinging on a coast are not necessarily produced by local winds in 

 coastal waters. They may be produced by distant weather systems and reach 

 the coast after traveling some distance, up to thousands of kilometers, outside 

 the area in which they were generated. Such waves are called swells, while 

 waves still within the area of generation are called seas. Swells have a longer 

 period, or time of passage between two successive wave crests, and move 

 faster than locally generated waves. Swells undergo a decay process in which 

 the height becomes progressively less with distance traveled, although they 



10 



Chapter 2 Relevant Processes and Factors 



