Chap 11.2 Ocean Currents

Ocean Current

A large amount of ocean water that moves in a particular and unchanging direction. There are 20 major ocean currents

Waves

Create beaches by carrying sediment and form steep and rocky cliffs all because of erosion and deposition.

Tides

Daily cycle of rising and falling ocean water. Tides are caused by gravitational attraction between the earth and the moon.

What do currents carry?

Dissolved minerals, solar energy, oxygen, and carbon dioxide.

The Coriolis Effect

Earth spins from west to east. As winds and currents move over this spinning body, their paths get redirected depending on which side of the equator they're on. For a person in the northern hemisphere, the winds and currents would be deflected to the right (clockwise)(East). For a person in the southern hemisphere, the winds and currents would be deflected to the left (counter clockwise)(West)

Salinity near the poles...

Is higher (during winter) because water is solidifying I to ice which leaves behind salt.

Salinity near the equator...

Is higher because the temperature is warmer. The ocean water is constantly evaporating and it leaves behind salt, which makes the water saltier.

Salinity near the poles...

Is lower (during summer) because ice is melting and the freshwater from the ice dilutes the ocean water.

What causes deep water currents to move?

It is caused by temperature and salinity of the water.

What causes surface currents to move?

It is caused by wind action, Earth's spin, and the shape of the continents. Also, the speed, direction, and volume of water can be affected by the uneven heating of the atmosphere.

Deep water currents

It is from 200m and deeper. It is caused by temperature and salinity of the water.

Surface currents

It is from the surface to 200m deep. It is caused by wind action, Earth's spin, and the shape of the continents.

Swells

Large rolling waves in open ocean water caused by wind action. Some are only a few meters high but others have been recorded at over 30m high.

Plankton

Microscopic plants and animals that are an essential food source for all the other organisms in the ocean.

Spring tides

Occur when the moon and sun are in line with each other. The water is pulled out to the sides of the Earth (left and right). The gravitational force is strongest.

Bays

Parts of the coast that indent. They are hit with less impact and waves deposit some sediment there.

Headlands

Parts of the coast that stick out and are hit by waves with more impact than Bays. They are typically composed of hard rock than the surrounding land.

What is the largest ocean current?

The Antarctic Circumpolar Current is in the southern ocean. It is 24 000km long and circles the entire continent of Antarctica. Each year it carries 100x more water than all the rivers on Earth combined. 3 million cubic km.

Salinity

The amount of salt in the ocean effects density. The more salt the more density. Saltier water is at the bottom of the ocean.

Wind action

The force of wind blowing over the top of the Earth.

Tsunami

The largest and most powerful wave caused by tectonic plate movement, earthquakes, landslides into the water and volcanic eruptions near water.

Upwelling

The rising of water from the deep. Upwelling brings nutrient-rich waters to the surface which feeds plankton, one of the main food sources for fish and other organisms.

Thermocline

The second layer of the ocean where the temperature rapidly decreases. It can reach the depths of 1 km below the ocean surface.

Shape of the continents

The shape of the continents also effect the movement of surface currents. Similar to how rocks and pebbles in a stream effect how the water flows. Even though the world's ocean water is connected, we treat it as five different ocean basins separated by the natural barriers of the continents.

Deep water

The third and final layer of the ocean. Temperatures are only about 2 degrees C above freezing

The ocean's layers

There are three different layers. the first is the surface (or mixed layer), the second is the thermocline, and the third is the deep water.

Density Current

When the mass of more dense (cold) seawater sinks beneath less dense (warm) seawater. By constantly moving large masses of water around, density currents create everything from excellent ocean fishing to bizarre weather.

Wind

Winds are the result of air moving rapidly from one area to another because of temperature differences. As air is heated by the sun, the particles gain energy and expand. This makes them less dense so they rise. When that happens cooler and denser air moves into the area left empty by rising air. As this moving air crosses over the ocean's surface, its energy is transferred to the water molecules causing the ocean water to move.

Neap tides

occur when the moon and sun are at right angle with each other. The gravitational attraction isn't as strong as spring tides. The water is pulled at the top and bottom of the Earth.