9Ocean Circulation Patterns Large central area in the middle of the gyre is a zone of calmer waters. Around the Antarctic there are no continents to deflect the current so it is a continuous circulation.
21Deep Ocean Circulation Water at the surface can become colder and more salty which will make it denser.The dense water sinks toward the ocean bottom, displacing lighter water.
22Deep Ocean Circulation This mainly occurs in the Arctic and Antarctic, where temperatures are low enough sea ice forms. Salts don’t get frozen in the ice making the surrounding water saltier.Deep ocean currents are difficult to measure and so little is known about them.
23TidesDaily change in the elevation of the ocean surface.
24Causes of TidesOcean tides result from the gravitational attraction exerted upon the Earth by the moon and to a lesser extent by the sun.
26Causes of TidesTidal bulges remain in place while Earth “rotates” through them. In one day the Earth experiences one high tide and one low tide. The tides migrate as the moon revolves around the Earth, shifting about 50 minutes a day.The tide generating power of the Sun is less than half that of the moon
31Causes of TidesDuring the first and third quarters the sun and moon act at right angles and offset the influence of each other. These are called neap tides.
32Types of TidesSemidinural - Two high and two low tides daily, with small differences in the high and low water heightsDinural - one high and one low tideMixed – usually two high and two low with a large inequality between high water heights and low water heights
37Tidal CurrentsHorizontal flow of water accompanying the rise and fall of the tidesFlood currents – tidal currents that advance into the coastal zoneEbb currents – currents generated by seaward moving waterSlack water – periods of little or no current