Ocean Movements EES Unit 4.2

Three Ways the Ocean Moves Waves Tides Currents

Waves Waves form because of the wind When wind is very strong When wind blows for a long time When wind blows over a long distance

Waves are a transfer of energy Energy from molecule to molecule http://www.onr.navy.mil/focus/ocean/motion/w aves1.htm Water molecules stay in place and rotate http://earthguide.ucsd.edu/earthguide/diagram s/waves/swf/wave_wind.html http://en.wikipedia.org/wiki/File:Deep_water_w ave.gif

Individual water molecules stay in place and rotate

Near the shore Waves break because they get too large for their base to support http://commons.wikimedia.org/wiki/File:Shallo w_water_wave.gif http://science.kqed.org/quest/video/science- of-big-waves/ Large waves caused by earthquakes are called tsunami http://www.youtube.com/watch?v=StdqGoezN rY&feature=channel http://science.kqed.org/quest/video/scary- tsunamis/

Tides Daily tides The daily rise and fall of sea level is called a tide Tides are caused by: Gravity pull from the moon (primary reason) Moon has greater effect because it is closer than the Sun Gravity pull from the Sun (secondary reason)

Remember: this area between high and low tide is also called the intertidal zone

High tides Moon pulls water on closest side Moon also pulls the Earth, leaving water on the other side behind Difference between high and low tide is called tidal range Low tides On opposite sides of Earth from where high tides occur http://www.pbs.org/wgbh/nova/earth/wha t-causes-the-tides.html

Monthly tides Spring tides Whenever the moon is in its full or new moon phase Tides will be higher than normal Neap tides When the moon, Earth, and Sun are 90 degrees to one another Tides are at their lowest http://oceanservice.noaa.gov/education/kits/ti des/media/supp_tide06a.html http://www.onr.navy.mil/focus/ocean/motion/t ides1.htm

Spring tides When Earth, moon, and Sun are in line with one another (during new and full moon)

Neap tides When Earth, moon, and Sun are at 90 degree angles (first or last quarter)

Ocean Currents Surface currents Caused by: Global wind patterns Rotation of the Earth The Coriolis effect Equator receives more heat than poles Heat travels north and south from the equator Wind + Rotation = Coriolis effect Causes currents to move toward the right in the Northern Hemisphere and left in the Southern Hemisphere NOTE: Study the diagram of the Coriolis effect to understand it

The Coriolis Effect

https://www.youtube.com/watch?v=Wda7azMvabE Shape of ocean basins Can travel thousands of miles and reach down hundreds of feet https://www.youtube.com/watch?v=Hu_Ga0JYFNg Local surface currents Longshore currents Caused by the wind not blowing exactly straight in to shore Rip currents Carry water from shore out to sea Very dangerous – if caught in one, swim parallel to shore until free Effects on climate Can raise temperatures of colder areas by as much as 30°F

The shape of the major ocean basins has a big effect on the direction that currents move.

The major gyres in the world’s oceans

Gulf Stream Current is what keeps water in the Carolinas warmer throughout the year

Deep ocean (thermohaline) currents Thermo = temperature Haline = salinity Deep ocean water movement is driven by temperature and salinity Happens at the surface Equator = warmer while poles = colder Cold, dense water sinks in certain places At the north pole and Antarctica This is called downwelling

Thermo = temperature Haline = salt

Cold, dense water moves along the ocean bottom Water must rise in other places This is called upwelling Usually happens along coastlines Upwelling brings nutrients and ocean life to the surface GREAT fishing areas

Upwelling: when wind pushes water away while deeper, colder water takes its place

Areas of major upwelling on Earth These areas have huge biodiversity because of nutrients coming up from deep in the ocean