Blogs & White Papers
What causes ocean currents? Ocean currents can be caused by wind, density differences in water masses caused by temperature and salinity variations, gravity, and events such as earthquakes or storms. Currents are cohesive streams of seawater that circulate through the ocean. Besides gravity, the most important forces that cause and affect ocean currents are horizontal pressure-gradient forces, Coriolis forces, and frictional forces. Temporal and inertial terms are generally of secondary importance to the general flow, though they become important for transient features such as meanders and eddies.
A rubber duck washed up on the beach after being carried out in the ocean. This lists the logos of programs or partners of NG Education which have provided or contributed the content on this page. Powered by. Ocean water is constantly moving, and not only in the form of waves and tides. Ocean currents flow like vast rivers, sweeping along predictable paths. Some ocean currents flow at the surface; others flow deep within water. Some currents flow for short distances; others cross entire how to edit flash files.swf basins and even circle the globe.
By moving heat from the equator toward the poles, ocean currents play an important role in controlling the climate. Ocean currents are also critically important to sea life. They carry nutrients and food to organisms that live permanently attached in one place, and carry reproductive cells and ocean life to new places. Rivers flow because of gravity. What makes ocean currents flow? Tides contribute to coastal currents that travel short distances.
Major surface ocean currents in the open ocean, however, are set in motion by the wind, which drags on the surface of the water as it blows. The water starts flowing in the same direction as the wind. But currents do not simply track the wind.
Other things, including the shape of the coastline and the seafloor, and most importantly the rotation of the Earth, influence the qhat of surface currents. In the Northern Hemisphere, for example, predictable winds called trade winds blow from east to west just above the equator. The winds pull surface water with them, creating currents. As these currents flow westward, the Coriolis effect —a force that results from the rotation of the Earth—deflects them.
The currents then bend to the right, heading north. At about 30 degrees north latitude, a different set of winds, the westerlies, push the currents back to the east, producing a closed clockwise loop. The same thing happens below the equator, in the Southern Hemisphere, except that here the Coriolis effect bends surface currents to the left, producing a counter-clockwise loop.
Large rotating currents that start near the equator are called subtropical gyres. These surface currents play an important role in moderating climate by transferring heat from the equator towards the poles. Subtropical gyres are also responsible for concentrating plastic trash in certain areas of the ocean. In contrast to wind-driven surface currents, deep-ocean currents are caused by differences in water density.
It all starts with surface currents carrying warm water north from the equator. The water cools as it moves into higher northern latitudes, and the more it cools, the denser it becomes. In the North Atlantic Ocean, near Iceland, the water becomes so cold that sea ice starts to form. The salt naturally present in seawater does not become part of the ice, however. It is left behind in the ocean water that lies just under the ice, making that water extra salty and dense.
The denser water sinks, and as it does, more ocean water moves in to fill the space it once occupied. This water also cools and sinks, keeping a deep current in motion. These currents circulate around the globe how to pray for your adult children a thousand-year cycle.
The Coriolis effect makes storms swirl clockwise in the Southern hemisphere and counterclockwise in the Northern Hemisphere. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited. Tyson Brown, National Geographic Society.
National Geographic Society. Andre Gabrielli, National Geographic Society. For oc on user permissions, please read our Terms of Service. If you have questions about licensing content on this page, please contact ngimagecollection natgeo. If you have questions about how to cite anything on our website in your project or classroom presentation, please what to do if you get burned with hot water your teacher.
She or he will best know the preferred format. When you reach out to him or her, you will need the page title, URL, and the date you accessed the resource. If a media asset is downloadable, a download button appears in the corner of the media viewer.
If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of What are stitch markers in knitting. Any interactives on this page can only be played while curtents are visiting our website.
You cannot download interactives. Plastic is ubiquitous in our everyday lives. Some plastics we can reuse or recycle—and many play important roles in areas like medicine and public safety—but other items, such as straws, are designed for only one use. In fact, more than 40 percent of plastic is used only once before it is thrown away, where it lingers in the environment for a long, long time.
It often breaks down into smaller and smaller particles, called microplastics, which can be ingested by both occean and people. Fortunately, there are things we can do to help—like stop using plastic bags, straws, and bottles, recycling when thee can, and disposing of waste properly.
Use these classroom resources to teach about ocean plastics and check back for more how to budget to pay off debt later this year!
Scientists across the globe are trying to figure out why the ocean is becoming more cutrents and what, if anything, can be done about it. Ocean currents, including the ocean conveyor belt, play a key role in determining how the ocean distributes heat energy throughout the planet, thereby regulating and stabilizing climate patterns.
A current is the steady, predictable movement of a fluid within a larger body of that fluid. Fluids are materials capable of flowing and easily changing shape. A gyre is a circular ocean current formed by the Earth's wind patterns and the forces created by the rotation of the planet. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Image Rubber Duck on the Beach A rubber duck washed up on the beach after being carried out in the ocean.
Twitter Facebook Rhe Google Caudes. Encyclopedic Entry Vocabulary. Coriolis effect. Media Credits The audio, illustrations, rhe, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
Media If a media asset is downloadable, a download button appears in cyrrents corner of the media viewer. Text Text on this page is printable and can be used according to our Terms of Service. Interactives Any interactives on this page can only be played while you are visiting our website. Related Resources. Plastic Pollution.
What are the causes of ocean currents Collection. Ocean Currents and Climate. View Video. View Article. Ocean Gyre. Educational Resources in Your Inbox. Educational Resources in Your Current Join our community of educators and receive the latest information on National Geographic's resources for you and your students.
The Earth's spin causes winds and ocean currents to curve right (clockwise) in the Northern Hemisphere, and left (counter clockwise) in the Southern Hemisphere, resulting in bended tracks. These major spirals of ocean-circling currents are called “gyres” and occur north and south of the Equator. Various processes cause surface water to move, but the primary driving force is wind. Wind blowing across a body of water transfers some of its momentum onto the surface of the water, causing it to move. On a smaller scale, this causes waves and on a global scale, this sets in motion large currents that can traverse an entire ocean. 1. Differences in water density, resulting from the variability of water temperature (thermo) and salinity (haline), also cause ocean currents. This process is known as thermohaline circulation. In cold regions, such as the North Atlantic Ocean, ocean water loses heat .
In this episode: You know about ocean tides, but how much do you know about ocean currents? Watch our three-minute video podcast to learn what puts the motion in the ocean. The ocean never stands still.
Even here in this quiet marina, you can see the water is slowly moving. If you stood at this spot for many hours, you'd witness one of the most reliable and predictable features of the ocean: the rise and fall of the tide, caused by the gravitational pull of the moon and the sun on our planet. But what's causing the motion you see here with this gently swaying anemone on the sea floor off the Atlantic Coast?
This is ocean current. The reason we have currents in the ocean is a bit more complicated. Tidal currents are strongest near the shore, in bays, and in estuaries along our coasts. This illustration will give you an idea of how this works. As the tide rises, water moves inland. This is called a flood current. As the tide recedes, the water moves seaward. This is called an ebb current. You can see the movement of water by watching the green seaweed.
Now let's zoom out and look at what's happening near the surface of the ocean on a global scale over time. At this scale, currents are driven primarily by two different forces. The first force is something we all know: wind. It shows surface ocean currents around the world during the period from June to December Check our show notes for a link to the full animation.
Let's take a few moments to look at a few prominent surface ocean currents. See that? You've probably heard of this current. It's called the Gulf Stream. The Gulf Stream is an intense, warm ocean current in the western North Atlantic.
It transports nearly four billion cubic feet of water per second. Coming into view now is the Kuroshio Current, located off the east coast of Japan. This is the ocean's largest current. It can travel between miles a day and is equal in volume to 6, large rivers.
Surface ocean currents on the open ocean are fantastically complicated and beautiful, driven by a complex global wind system. But there's one more ocean current force that you may have never heard of. It's called thermohaline circulation.
Thermo means 'heat,' and 'haline' refers to salinity. This term describes how changes in heat and salt content constantly change the density of ocean water.
Cold, salty water is dense and sinks to the bottom of the ocean and eventually returns to the surface through mixing and wind driven upwelling. On a global scale, this sinking and rising of ocean water creates what scientists call the 'great ocean conveyor belt.
This conveyor belt affects the Earth's climate by driving warm water from the Equator and cold water from the poles around the Earth.
It takes water almost years to move through the whole conveyor belt. So there you have it. Tides, wind, heat, and salinity are all factors that put the motion in the ocean. From corals to coastal science, catch the current of the ocean with our audio and video podcast, Making Waves. Subscribe to Feed Subscribe in iTunes. Ocean Currents Making Waves: Episode