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Transcript of Ocean Currents
are large amounts of ocean water that move in a particular and unchanging direction, similar to a river. There are more than 20 major ocean currents in the world. These currents carries and transport minerals all over the place, like important ones that we and other creature need (oxygen, carbon dioxide, solar energy) as well as organisms like
(microscopic organism that are essential food for fish and other organisms), fish and whales.
This presentation is by:
Zack Ducey, Alfonso Pineda, and Jason Ueng
Thanks for listening!
There's a lot of currents around the world,
with the Antarctic Circumpolar Current (ACC) being
the largest one. This current circles the entire Antarctica,
it's 24 000 kilometers long, and it carries around 3 million cubic kilometers of water, which is 100 times more than all of the Earth's river combined!
Did you know?
Did you know that the word plankton originates from an ancient Greek word meaning wanderer. The same word is the root for the word "planet".
Types of Ocean Currents
There are 2 types of ocean currents:
(occur on average depth of 200 meters and higher) and
Deep Water Currents
(occur deeper than 200 meters). Both have major effects on the ocean ecosystems and human activities.
What Makes Surface Currents Move?
There are 3 causes of surface current:
(The force of wind blowing over the top of the water), the Earth's rotation, and shape of the continents. But how do these causes make surface currents?
What Makes Deep Currents Move?
Ocean water doesn't always have the same temperature because of the density differences (colder water is denser than warm water therefore is sinks beneath warm water). The sinking and movement of dense water beneath surface water is called density current.
can create from ocean fishing, to bizarre weather. There are 3 layers to ocean water. The top layer being the surface layer (or mixed layer), with the next layer being the
in which the temperature drops dramatically because the Sun's energy can't heat, and finally the last layer being the deep water which the temperature can be 2 degrees Celsius.
How ocean waves move and their effects on shaping lands
Ocean waves are large ripples caused by winds, which is another way that ocean water moves. The faster the wind and the longer it blows, the larger area covered, and the bigger the waves.
are large, rolling waves that formed in the open ocean. The largest waves in the ocean are created by earthquakes on the ocean floor (forming a
), a landslide (when land slides into the ocean), or a volcanic eruption. Waves also can erode (or carve away) hard rocks and deposit sediments on shore. Ocean waves depend on the shape of the coastline when it reaches a coastline. Sections of coastlines that extend out into the ocean are called
. These can reduce the energy of the incoming waves and leave them with less energy to erode. Bays are areas the waves go onto and leave sediments.
Other than water temperature, salinity in ocean water affects the movement of density current. Recall from the previous chapter, salinity is the amount of salt dissolved in water, which causes the difference in density. So ocean water changes density when fresh water is added to it (which decreases salinity) or the processes of evaporating water and freezing it (which increases salinity). From these points of causing deep ocean currents to move, eventually either cold water is warmed and less dense or colder water is pushing the other water up. The rising of water from the deep is called
. Upwelling can bring food up the organisms and other sources up.
What are tides and how do they occur?
is the daily cycle of ocean water rising and falling. It happens because of the gravitational attraction between Earth and Moon. That's because Earth and Moon are close together in space so the Moon's gravity pulls the Earth's ocean upwards, creating a high tides. At the same time, the side of Earth's opposite of the Moon also experience a high tide, and the other 2 sides experience low tides. So there's going to be 2 occurrence of high tide and low tide in a day. The difference between high and low tide is called the tidal range, and the shape of the coastline effects it. Another thing about tides, the Sun also help make Earth's tides. Because the Sun is far, the gravitational pull of water on Earth is about half as much as the Moon's. So when both Sun and Moon lines up, it creates spring tides (very high and very low tides). When the Sun and Moon aren't lined up, they are called neap tides.
Did You Know?
The highest tide record in the world is located in Minas Basin, Nova Scotia, Canada. The maximum tidal range was recorded 16.8 meters, or 54.6 feet!
The first cause for the movement of surface current is that, the speed and path of the wind links to the speed and path of the surface current because air is heated from the Sun and rises with the cooler air replacing it since warm air is less denser than cooler air.
The effect of rotation pushes currents from the Northern Hemisphere to the right (east) and Southern Hemisphere to the left (west) since is Earth is moving from west to east (counter clockwise). The change of direction is called the
The third factor affecting the movement of ocean surface currents is the shape of the continents. Just like large rocks in a stream affect the path of water in a stream, continents affect how and where surface currents will move.