17Neap TidesNeap tides are especially weak tides. They occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth). Neap tides occur during quarter moons.
19Tide levels in the port of Brest (France) in Dec 2000 Tide levels in the port of Brest (France) in Dec The illustration shows the alternating high and low tides and, over a month, the variations in amplitude due to the respective positions of the Moon and Sun.
27Origin of waves Most waves wind-driven Moving energy along ocean/air interfaceWind main disturbing forceBoundary between and within fluids with different densitiesAir/ocean interface (ocean waves)Air/air interface (atmospheric waves)Water/water interface (internal waves)
28Wind Generation of Waves The type of wave generated by wind is determined by:Wind velocity (how fast)Wind duration (how long)Fetch (distance over which wind blows)Simply put, wave size increases as the strength and duration of the wind, and distance over which it blows increases.
29Internal waves Associated with pycnocline Larger than surface waves Caused by tides, turbidity currents, winds, shipsPossible hazard for submarinesFig. 8.1a
30Internal waves form within the water column on the pycnocline.