Ocean Currents Ocean Currents is about the causes

Ocean Currents

“Ocean Currents” is about: • the causes, effects, and characteristics of surface currents and deep currents.

Ship Question The picture below shows the triangle trade route in the 1500 s Why did ships sail in this clockwise direction? Hint: Look at the next slide.

Name the Earth’s Oceans!!!

Earth’s Oceans • They are considered separate oceans because water in these regions follow a particular pattern and behavior.

What is a current? • A word that describes streamlike movements of water in the ocean

Surface Currents • These are currents that are on the top layer of the ocean (up to several hundred meters deep). • They are caused mainly by the wind that occurs at the ocean’s surface. • They are also controlled by the Coriolis effect and continental deflections.

Global Winds • Winds that blow across the Earth’s surface • The force of these winds move the water • Different winds cause currents to flow in different directions • Winds near the equator move east to west • Winds near the poles move west to east

Coriolis Effect • The apparent curving of the path of a moving object from an otherwise straight path due to the Earth's rotation.

Continental Deflection �If the earth’s Surface were covered completely in water, the currents would travel freely across the globe in a very uniform pattern. �We have huge land masses on our Earth called continents. When surface currents meet continents, the currents deflect, or change direction.

Currents are Affected by Temperature �Warm-water currents begin near the equator and carry warm water to other parts of the ocean. �Cold-water currents begin closer to the poles and carry cold water to other parts of the ocean.

Gyres – A ring like system of ocean currents

SURFACE CURRENTS • SURFACE CURRENTS ARE EXTREMELY SIGNIFICANT BECAUSE THEY AFFECT CLIMATE AND WEATHER. ONE WARM-WATER SURFACE CURRENT, THE GULF STREAM, HELPS TO MODERATE TEMPS ALONG THE EAST COAST OF THE U. S. THE WARM WATER ALSO HELPS TO FEED LARGE STORMS LIKE HURRICANES. • A COLD WATER SURFACE CURRENT CALLED THE CALIFORNIA CURRENT RUNS SOUTHWARD ALONG THE WEST COAST. THIS COLD WATER CURRENT PREVENTS HURRICANES FROM FORMING ON THE WEST COAST. THE WATER ISN’T WARM ENOUGH TO FUEL A HURRICANE.

Deep Ocean Currents • A stream like movement of water FAR below the surface.

Deep Ocean Currents �Formed in parts of the ocean where water density changes. The density of the ocean water is affected by temperature and salinity The colder the water is…the more dense The higher the salinity of the water… the more dense the water is

Deep Ocean Currents �Denser (Colder and higher salinity levels) water sinks!

What causes density changes in ocean water? �Surface currents carry the warmer, less-dense water from other ocean regions to the poles �Once the temperature gets colder and the salinity levels increase (as water freezes it squeezes out the salt), the water becomes more dense and sinks �Deep ocean currents carry the cold, dense water across the ocean floor from polar regions to other regions in the ocean �Once the water warms and its salinity levels decrease, it becomes less dense and rises

Deep Currents – How they work! • Deep currents form at the poles where water is extremely cold, increasing its density. • Under polar ice, water is extremely high in salinity, increasing its density. Ice is fresh water – no salt is allowed to stay. • Copy this: Ocean water near the poles is extremely cold and has high salinity, making it very dense, so it sinks to the ocean floor, moving along very slowly toward the equator.

Deep Currents: ADD THIS TO YOUR DOUBLEBUBBLE web. • Why are deep currents important? ? 1. Deep currents pick up nutrients and organic material as they move along the ocean floor. The nutrients will eventually feed plankton. They are critical for upwelling. In areas of upwelling, the deep ocean currents are forced to the surface by the landmasses, bringing these nutrients with them. 2. Deep currents help with heat transfer around the Earth.

Surface Currents: ADD THIS TO YOUR DOUBLEBUBBLE web. • Why are surface currents important? ? ? 1. Surface currents impact climate. Warmer currents bring warmer climates; colder currents bring colder climates. 2. Surface currents aid in trade and travel.

The California Current brings cooler temperatures along the west coast. The Gulf Stream brings warmer temperatures along the east coast.