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 in 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.
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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 animals and people. Fortunately, there are things we can do to help—like stop using plastic bags, straws, and bottles, recycling when we can, and disposing of waste properly.
Use these classroom resources to teach about ocean plastics and check back for more coming later this year! Scientists across the globe are trying to figure out why the ocean is becoming more violent and what, if anything, can be done about it. Currents driven by thermohaline circulation occur at both deep and shallow ocean levels and move much slower than tidal or surface currents.
Currents affect the Earth's climate by driving warm water from the Equator and cold water from the poles around the Earth. The warm Gulf Stream , for instance, brings milder winter weather to Bergen, Norway, than to New York, much further south. Home Ocean Facts What is a current?
What is a current? The term "current" describes the motion of the ocean. Because of Coriolis effect, the water goes right in the Northern Hemisphere and left in the Southern Hemisphere.
You can see on the map of the major surface ocean currents that the surface ocean currents create loops called gyres Figure below. The Antarctic Circumpolar Current is unique because it travels uninhibited around the globe. Why is it the only current to go all the way around? The ocean gyres. Why do the Northern Hemisphere gyres rotate clockwise and the Southern Hemisphere gyres rotate counterclockwise? Even though the equator and poles have very different climates, these regions would have more extremely different climates if ocean currents did not transfer heat from the equatorial regions to the higher latitudes.
The Gulf Stream is a river of warm water in the Atlantic Ocean, about kilometers wide and about a kilometer deep. Water that enters the Gulf Stream is heated as it travels along the equator. London, U. Because air traveling over the warm water in the Gulf Stream picks up a lot of water, London gets a lot of rain.
In contrast, Quebec is much drier and receives its precipitation as snow. In a satellite image of water temperature in the western Atlantic it is easy to pick out the Gulf Stream, which brings warmer waters from the equator up eastern North America. Deep Currents Thermohaline circulation drives deep ocean circulation.
Thermo means heat and haline refers to salinity. Differences in temperature and in salinity change the density of seawater.
So thermohaline circulation is the result of density differences in water masses because of their different temperature and salinity. What is the temperature and salinity of very dense water? Lower temperature and higher salinity yield the densest water. When a volume of water is cooled, the molecules move less vigorously so same number of molecules takes up less space and the water is denser.
If salt is added to a volume of water, there are more molecules in the same volume so the water is denser. Changes in temperature and salinity of seawater take place at the surface. Water becomes dense near the poles. Cold polar air cools the water and lowers its temperature, increasing its salinity.
Fresh water freezes out of seawater to become sea ice, which also increases the salinity of the remaining water. This very cold, very saline water is very dense and sinks. This sinking is called downwelling. This video lecture discusses the vertical distribution of life in the oceans. Two things then happen. The dense water pushes deeper water out of its way and that water moves along the bottom of the ocean.
This deep water mixes with less dense water as it flows.
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