Weather Facts: North Atlantic Drift (Gulf Stream) | weatheronline.co.uk Weather Facts | Wind of the World | Climate of the World | Weather Lore | Weather Brains | Philip Eden | Oil spill | Fukushima | Volcanic ash | Video North Atlantic Drift (Gulf Stream) The Gulf Stream is the most important ocean-current system in the northern hemisphere, which stretches from Florida to north-western Europe. It incorporates several currents: the Florida current, the Gulf Stream itself, and an eastern extension, the North Atlantic Drift. The Florida Current is fast, deep, and narrow, but after passing Cape Hatteras the Gulf Stream becomes less effective at depth and develops a series of large meanders which form, detach, and re-form in a complicated manner. After passing the Grand Banks (off Newfoundland), the flow forms the diffuse, shallow, broad slow-moving North Atlantic Drift. The relatively warm waters of the North Atlantic Drift are responsible for moderating the climate of western Europe, so that winters are less cold than would otherwise be expected at its latitude. Without the warm North Atlantic Drift, the UK and other places in Europe would be as cold as Canada, at the same latitude.

For example, without this steady stream of warmth the British Isles winters are estimated to be more than 5 °C cooler, bringing the average December temperature in London to about 2°C. Within the Gulf of Mexico , the Gulf Stream is very narrow, only 50 miles wide, and travels very fast at 3 mph, carrying water at about 25°C. The North Atlantic Drift widens considerably to several hundred miles, slows to less than 1 mph and splits into several sub-currents. Off the British Isles it splits into two branches, one going south (the Canary Current) and the other going north along the coast of W and N Europe, where it exerts considerable influence upon the climate as far as northwestern Europe. For example, the Drift is particularly important because it keeps many Norwegian ports free of ice throughout the year. The two main driving forces behind it are the prevailing southwesterly trade winds and the circulation of the water far below the oceans surface, the North Atlantic Deep Water (NADW) circulation. Water in the north Atlantic sinks because it is dense. Density of water is increased by both salinity and temperature - the colder and saltier the water is the denser it is.

This deep water flows to the Gulf of Mexico until it warms enough to resurface and flow back north as the Gulf Stream. Some 11,000 years ago the NADW shut down in response to subtle shifts in global climate. This slowed and diverted the course of the Gulf Stream to such an extent that the regional climate of the Northeast Atlantic became considerably cooler. As a result Northwestern Europe dropped back to ice age conditions within tens of years. It is now suspected that global warming may trigger a shutdown in the NADW, and a slowing or diversion of the Gulf Stream, which would ironically lead to colder climates throughout the UK and Northwest Europe. Advertisement Gulf Stream | ocean current | Britannica.com ocean current Alternative Title: Gulf Stream-North Atlantic-Norway Current Related Topics Henry Melson Stommel Gulf Stream, warm ocean current flowing in the North Atlantic northeastward off the North American coast between Cape Hatteras , N.C., U.S., and the Grand Banks of Newfoundland, Can. In popular conception the Gulf Stream also includes the Florida Current (between the Straits of Florida and Cape Hatteras) and the West Wind Drift (east of the Grand Banks).

The Gulf Stream is part of a general clockwise-rotating system of currents in the North Atlantic. It is fed by the westward-flowing North Equatorial Current moving from North Africa to the West Indies . Off the northeastern coast of South America , this current splits into the Caribbean Current , which passes into the Caribbean Sea and through the Yucatán Channel into the Gulf of Mexico , and into the Antilles Current , which flows to the north and east of the West Indies. The Caribbean Current reemerges into the Atlantic through the Straits of Florida between the Florida Keys and Cuba to form the Florida Current. Deflected to the northeast by the submerged Great Bahama Bank southeast of the Florida Peninsula, this swift current is joined by the Antilles Current and flows roughly parallel to the eastern coast of the United States to about Cape Hatteras. There the path of the Gulf Stream becomes twisted as huge swirls of warm water break off. A part of the Gulf Stream forms a countercurrent that flows south and then west. The countercurrent rejoins the Gulf Stream on its seaward side along the coast of Florida and the Carolinas.

climate (meteorology): The Gulf Stream The main portion of the Gulf Stream continues north, veering more to the east and passing close to the Grand Banks, south of Newfoundland, where it breaks up into swirling currents. Some of these eddies flow toward the British Isles and the Norwegian seas and form the North Atlantic Current (or Drift). A larger number flow south and east, either becoming part of westward-flowing countercurrents or joining the Canary Current . History of scientific study Irminger Current The Gulf Stream was first described by the Spanish navigator and explorer Juan Ponce de León early in the 16th century. In the late 1700s Benjamin Franklin produced a map of the current. In 1844 systematic surveying of the stream was begun by the United States Coast and Geodetic Survey. Concentrated modern efforts were inaugurated only in the early 1930s by the ketch Atlantis of the Woods Hole Oceanographic Institution in Massachusetts . Map of the Gulf Stream drawn by Benjamin Franklin. Library of Congress, Washington, D.C. One of the difficulties of scientific study of the Gulf Stream is its extremely complex makeup.

It is not a simple ribbon of moving water but rather a complicated network of currents that tend to shift course over time, to disappear and then reappear, and to develop eddies along the margins. Today, orbiting space satellites are utilized to map the path of the Gulf Stream. The satellites are equipped with sensors that can detect temperature and colour variations to trace the changing surface patterns of the current. Movement and physical features Most of the waters that enter the Gulf Stream system first have been driven westward across the Atlantic by the Northeast Trade Winds . In the Caribbean and the Gulf of Mexico the current is gradually narrowed, and its velocity increases to more than 3.5 knots (4 miles [6.5 km] per hour) as it passes through the Straits of Florida. The volume of flow there has been measured at 1,060,000,000 cubic feet (30,000,000 cubic metres) per second, or many hundreds of times that of the Mississippi River . As it turns north between Florida and the Bahamas, the Florida Current flows at a depth of some 2,600 feet (790 m) and then follows the continental slope beyond the edge of the shelf.

Velocities gradually decrease to about one knot off Cape Hatteras. World Tour In the western Atlantic, the current’s deep-blue water, with its higher temperature and salinity, is readily distinguishable from surrounding waters, particularly along its well-defined western margin. The eastern edge gradually moves seaward as the current moves northward. The water between the current and the North American mainland, with its lower salinity and temperature, forms a boundary known as the Cold Wall. This water, overlying the continental shelf , frequently has a southerly flow, counter to that of the Florida Current. Britannica Stories Scientists Ponder Menopause in Killer Whales Off the coast of the United States, the Gulf Stream system separates the relatively warm and saline waters of the Sargasso Sea in the mid-Atlantic region from the colder waters to the west and north.

In winter, for example, average surface temperatures of the Gulf Stream off New England may be 20° F (11° C) higher than those of surface waters only 150 miles (240 km) to the northwest, although there is less than a 10° F (6° C) change in surface-water temperatures over a 1,000-mile (1,600-kilometre) distance to the southeast. Beyond Cape Hatteras the Gulf Stream broadens and moves into deeper water. There it crosses the Western Boundary Undercurrent, which consists of cold, southward-flowing water that sinks to considerable depths in the vicinity of Greenland. About 1,500 miles (2,400 km) northeast of Cape Hatteras, in the area of the Grand Banks, the warm Gulf Stream waters come close to the cold, southward-flowing Labrador Current . The contact of cold, humid air moving over the Labrador Current with the warm surface waters of the Gulf Stream causes widespread condensation. This climatic condition causes the region to have one of the highest incidences of fog in the world.

Moving out into the North Atlantic, the current becomes shallower and begins to break down into a meandering pattern of disconnected filaments flowing in the same general direction. Much of the initial force of the current has been dissipated by this time, and momentum is afforded primarily by the westerly winds. Part of the water there is diverted southward into the Sargasso Sea area. Near the middle of the ocean , the North Atlantic Current divides. One branch moves southeast and south as the relatively cool Canary Current, which flows past the Iberian Peninsula and northwestern Africa. The other branch (the balance of the North Atlantic Current) moves toward northwestern Europe. Effects on marine and human life Connect with Britannica BBC - Weather Centre - Climate Change - Gulf Stream Contact Us The Gulf Stream The world's oceans move constantly. Ocean currents flow in complex patterns and are affected by the wind, the water's salinity and temperature, the shape of the ocean floor, and the earth's rotation. The Gulf Stream is one of the strongest ocean currents in the world. It is driven by surface wind patterns and differences in water density. Surface water in the north Atlantic is cooled by winds from the Arctic. It becomes more salty and more dense and sinks to the ocean floor.

The cold water then moves towards the equator where it will warm slowly. To replace the cold equator-bound water, the Gulf Stream moves warm water from the Gulf of Mexico north into the Atlantic. The Gulf Stream brings warmth to the UK and north-west Europe and is the reason we have mild winters. Without this steady stream of warmth the British Isles winters are estimated to be more than 5C cooler, bringing the average December temperature in London to about 2C. At the end of the last Ice Age, when the ice sheet covering North America melted, the sudden increase in fresh water reduced the salinity of the north Atlantic surface water and therefore less 'dense water' sank and moved towards the equator. This reduced, or even shut-down completely, the warm Gulf Stream. Temperatures in north-west Europe fell by 5C in just a few decades. Recent observations have shown that since 1950 there has been a decrease of 20% in the flow of cold water in the Faeroe Bank channel between Greenland and Scotland. This is one source of cold dense water that drives the density-based component of the Gulf Stream.

There may be an increase in flow from other cold water sources, but, if not, it could be the start of the slow down of the Gulf Stream. The IPCC believe it is very likely that the Gulf Stream will slow down during the 21st Century but very unlikely it will undergo a ‘large abrupt transition’. The average reduction predicted by the various models used is 25%. This slowing will have a cooling effect but the temperature will still increase in the region overall. It suggests that the British Isles, especially western regions, will see a significantly smaller temperature increase than other areas of land mass. Water: Benjamin Franklin's Chart of The Gulf Stream The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates in the Gulf of Mexico, exits through the Strait of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean. At about 30°W, 40°N, it splits in two, with the northern stream crossing to northern Europe and the southern stream recirculating off West Africa.

The Gulf Stream influences the climate of the east coast of North America from Florida to Newfoundland, and the west coast of Europe. This warm water then flows up the Norwegian coast, with a westward branch warming Greenland's tip, at 60°NIt keeps northern Europe about nine to eighteen degrees warmer in the winter than comparable latitudes elsewhere. In this false-color Terra MODIS image, the Gulf Stream can be seen flowing to the northeast off of the United State’s eastern seaboard. This image is a false-color representation of water temperatures of the Atlantic, and since the Gulf Stream is a warm current, it shows up clearly against the surrounding waters. Temperatures are shown in a color range; progressing from low to high are purple, blue, turquoise, green yellow, orange, and red. Black represents a lack of data, and is used predominantly to represent land. The Gulf Stream shows up as a winding rope of orange and yellow against the cooler green and blue waters. NASA Pictured above is the East Coast of the United States, in grey, with the Gulf Stream, in orange, revealed through Sea Surface Temperature data (SST), made from the AVHRR (Advanced Very High Resolution Radiometer) sensor carried on a NOAA satellite.

In this image, purple and blue represent the coldest temperatures (between 0-15 °C) and orange and red represents the warmest temperatures (between 22-32°C). The Gulf Stream is easily visible as the warmest water in the image and reaches from the Carribbean to as far north as Delaware. Credit: Gulf Stream Tutorial. Climate Change could alter this. Because freshwater is less dense than seawater, increased precipitation, melting of polar glaciers and ice caps could block the system by reducing the amount of cold water that sinks downwards. As water travels through the water cycle, some water will become part of The Global Conveyer Belt and can take up to 1,000 years to complete this global circuit. It represents in a simple way how ocean currents carry warm surface waters from the equator toward the poles and moderate global climate. NASA Graphic In the Atlantic, warm, high-salinity water flows northward in the Gulf Stream along the east coast of North America. Some of this water continues northeastward in the North Atlantic Current toward Iceland and Norway. Off the coast of Greenland, a portion of the surface water cools, becomes dense, and sinks.

A further portion of surface water continues into the Arctic Ocean before also cooling and sinking. Together these sinking plumes off Greenland and in the Arctic form "deep water" that plays an important role in global oceanic circulation. Credit: NASA , UNEP, NSIDC,USGS Data compiled from The British Antarctic Study, NASA, Environment Canada, UNEP, EPA and other sources as stated and credited Researched by Charles Welch-Updated daily This Website is a project of the The Ozooe Hole Inc. UCSB Science Line UCSB Science Line How do ocean currents contribute to the change in climate? Answer 1: First off, certain famous ocean currents have well-known effects on climate. Consider the Gulf Stream. The climate in Northwestern Europe (the UK especially) is much more mild than it is directly across the Atlantic in Canada and the Northeastern US. There can be up to a 30-40 degree (Fahrenheit) air temperature difference in January between these two areas. The Atlantic Ocean near Canada is locked in ice in winter but the Atlantic Ocean near England is not. It is thought that the huge temperature difference is due to the Gulf Stream, one of the strongest currents in the ocean, and one of the best studied.

(Ben Franklin was one of the first people to map this current. You can check out information on Gulf stream History .) The Gulf Stream brings warm water from the Carribean and Florida north, along the coast of the US, and then east across the Atlantic to Europe. Because it takes a right-hand turn somewhere around North Carolina, the warming effect of its waters misses the Northeast US and Canada, but does reach England and Ireland. Take a look at some maps of the The Gulf stream and maps . Wheither or not you think that the relatively mild climate in England, Scotland, Wales, Ireland and Northern Ireland is due to the direct effect of the warm water in the Gulf Stream, or to the indirect effect of The Great Ocean Conveyor Belt ("thermohaline circulation"), of which the Gulf Stream is a part, either way the warming is partly caused by ocean currents. If the Gulf stream was to slow down considerably (as it has in the past), then winters in Europe would become very cold. The last time this happened, from 1450-1900, it was called The Little Ice Age .

There is some concern that current global warming caused by rising carbon dioxide concentrations will cause the polar ice cap to melt and slow down the Great Ocean Conveyor Belt, thus slowing down the Gulf Stream and sparking a cooling event in Western Europe. This is the (tiny bit of) science behind the movie "The Day After Tomorrow". Many scientists think this is unlikely, but recent research shown that past ice ages have been linked to slow downs in the Great Ocean Conveyor Belt. Check out Abrupt Climate Change . The Gulf Stream is just one example of how ocean circulation affects climate. It is a more complicated story. Winds are an important force driving ocean currents. Winds, in turn, are partly driven by differences in heat from one part of the globe to the next. As global warming affects the global heat budget, it will alter the strength and direction of winds, which will alter the strength and direction of the major ocean currents. We already see evidence for changes in ocean circulation due to global warming, but I don't think anyone knows enough about the complex interaction of winds, currents and the global heat balance to predict what will happen as more and more warming occurs.

As ocean currents change (and they will), not only will climate change, but marine ecosystems will change as well, with potentially dramatic effects on all ocean life, as well as on the human food supply. (More than 1 billion people rely on fish as their primary source of protein.) Answer 2: The contribution of the ocean currents to the climate exists, and it also works in the opposite direction. I mean, the climate also contributes to ocean currents. Ocean waters are constantly on the move. How they move influences climate and living conditions for plants and animals, even on land. Currents flow in complex patterns affected by wind, the water's salinity and heat content, bottom topography, and the earth's rotation. Surface water movement takes place in the form of currents. Currents move ocean water horizontally at the ocean's surface. Surface currents are driven mainly by the wind. Other forces such as the Coriolis effect and the location of landmasses do affect surface current patterns. The Coriolis Effect explains how the earth's spin causes the wind to curve. The wind in the northern hemisphere curves to the right and the wind in the southern hemisphere curves to the left.

In fact, huge circular patterns called current gyres can be seen when looking at the world's ocean currents. From the equator to middle latitudes, the circular motion is clockwise in the Northern Hemisphere and counterclockwise in the Southern hemisphere. Near the poles of the Earth, there is a tendency for the gyres to flow in the opposite direction. This circulation of water helps spread energy from the Sun. The Sun warms water at the equator and then water and heat are transported to higher latitudes. An example is El Nino. El Nino is a name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru. In El Nino years, the Equatorial counter current intensifies in the Pacific Ocean.This current flows towards the east, and it is a partial return of water carried westward by the North and South Equatorial currents. The effect of El Nino brings changes of weather raising or lowering air temperature, and amounts of rain. These factors contribute to change the weather in different places and in different forms. Answer 3: Currents flow in complex patterns affected by wind, the water's salinity and heat content, bottom topography, and the earth's rotation.

Upwelling brings cold, nutrient-rich water from the depths up to the surface. The earth's rotation and strong seasonal winds push surface water away from some western coasts, so water rises on the western edges of continents to replace it, which is why the ocean is so much colder on the east coast than the west coast. Marine life thrives in these nutrient-rich waters. Colder or saltier water tends to sink, so you can imagine that the waters off the coast of Antarctica are really cold. A global "conveyor belt" sets in motion when deep water forms in the North Atlantic, sinks, moves south, and circulates around Antarctica, and then moves northward to the Indian, Pacific, and Atlantic basins. It can take a thousand years for water from the North Atlantic to find its way into the North Pacific. Oceans store a large amount of heat, so small changes in ocean currents can have a large effect on coastal and global climate as they carry enormous amounts of heat north and south. Answer 4: Ocean currents move warm and cold bodies of water around.

Water has a specific heat capacity thousands of times that of air, and as a result are able to chill or heat the air over them, as well, as are the source of vapor that becomes clouds and precipitation.Simply enough, the Earth's air-flow patterns are atmospheric, but the air temperature and even moreso the precipitation depends on ocean currents. Answer 5: Oceans play a HUGE role in redistributing heat around the globe. Ocean surface water that is heated by the sun near the equator eventually makes its way to the high latitudes where it cools off. When it is cooled, it sinks. Eventually, that cooled water makes its way back to the equator where it wells up and becomes surface water again. The whole cycle then repeats itself. This system of upwelling, heating, cooling, and downwelling is called the global thermohaline circulation system. Itsprimary influence is to transfer heat from the equator to the highlatitudes. One fear related to global warming is that rapidly melting polar ice sheets could cause this circulation system to cease. Melting of ice sheets delivers huge influxes of fresh water to the polar oceans.

Because freshwater is less dense than sea water, it sits on the surface of the oceans and prevents the sinking that is necessary to drive the circulation system. The effect of this is that the higher latitudes (England, for example) would become much colder because no warm surface water would be brought to the poles and the lower latitudes (around the equator) would become warmer because there would be no upwelling of cold water. Click Here to return to the search form. Copyright © 2015 The Regents of the University of California, All Rights Reserved. The Gulf Stream in the Atlantic Ocean - Overview The Warm Ocean Current Flows from The Gulf of Mexico into the Atlantic Ocean The Gulf Stream results in beaches with warm water. Stockbyte/ Stockbyte/ Getty Images By Amanda Briney, Contributing Writer The Gulf Stream is a strong, fast moving, warm ocean current that originates in the Gulf of Mexico and flows into the Atlantic Ocean . It makes up a portion of the North Atlantic Subtropical Gyre. The majority of the Gulf Stream is classified as a western boundary current.

This means that it is a current with behavior determined by the presence of a coastline - in this case the eastern United States and Canada - and is found on the western edge of an oceanic basin. Western boundary currents are normally very warm, deep, and narrow currents that carry water from the tropics to the poles. The Gulf Stream was first discovered in 1513 by the Spanish explorer Juan Ponce de Leon and was then used extensively by Spanish ships as they travelled from the Caribbean to Spain. In 1786, Benjamin Franklin mapped the current, further increasing its usage. Path of the Gulf Stream Today, it is understood that the waters feeding into the Gulf Stream begin flowing off the west coast of Northern Africa (map) . continue reading below our video What are the Seven Wonders of the World There, the Atlantic North Equatorial Current flows from that continent across the Atlantic Ocean. Once the current reaches eastern South America, it splits into two currents, one of which is the Antilles Current. These currents are then funneled through the islands of the Caribbean and through the Yucatan Channel between Mexico and Cuba. Because these areas are often very narrow, the current is able to compress and gather strength.

As it does so, it begins circulating in the Gulf of Mexico’s warm waters. It is here that the Gulf Stream becomes officially visible on satellite images so it is said that the current originates in this area. Once it gains enough strength after circulating in the Gulf of Mexico, the Gulf Stream then moves east, rejoins the Antilles Current, and exits the area through the Straits of Florida. Here, the Gulf Stream is a powerful underwater river that transports water at a rate of 30 million cubic meters per second (or 30 Sverdrups). It then flows parallel to the east coast of the United States and later flows into the open ocean near Cape Hatteras but continues moving north. While flowing in this deeper ocean water, the Gulf Stream is its most powerful (at about 150 Sverdrups), forms large meanders, and splits into several currents, the largest of which is the North Atlantic Current. The North Atlantic Current then flows further north and feeds the Norwegian Current and moves the relatively warm water along the west coast of Europe. The rest of the Gulf Stream flows into the Canary Current which moves along the eastern side of the Atlantic Ocean and back south to the equator.

Causes of the Gulf Stream The Gulf Stream, like all other ocean currents is mainly caused by wind as it creates friction when moving over the water. This friction then forces the water to move in the same direction. Because it is a western boundary current, the presence of land along the Gulf Stream’s edges also aids in its movement. The northern branch of the Gulf Stream, the North Atlantic Current, is deeper and is caused by thermohaline circulation resulting from density differences in the water. Impacts of the Gulf Stream Because ocean currents circulate water of different temperatures all over the globe, they often have a significant impact on the world’s climate and weather patterns. The Gulf Stream is one of the most important currents in this regard since it gathers all of its water from the warm tropical waters of the Caribbean and the Gulf of Mexico. As such, it keeps sea surface temperatures warm, causing the areas around it to be warm and more hospitable. Florida and much of the Southeastern United States for instance is mild all year round. The greatest impact the Gulf Stream has on climate is found in Europe.

Since it flows into the North Atlantic Current, it too is warmed (though at this latitude the sea surface temperatures are cooled considerably), and it is believed that it helps keep places like Ireland and England much warmer than they would otherwise be at such a high latitude. For example, the average low in London in December is 42°F (5°C) while in St. John’s, Newfoundland, the average is 27°F (-3°C). The Gulf Stream and its warm winds are also responsible for keeping northern Norway’s coast free of ice and snow. As well as keeping many places mild, the Gulf Stream’s warm sea surface temperatures also aid in the formation and strengthening of many of the hurricanes that move through the Gulf of Mexico. Additionally, the Gulf Stream is important to the distribution of wildlife in the Atlantic. The waters off of Nantucket, Massachusetts for example are incredibly biodiverse because the presence of the Gulf Stream makes it the northern limit for southern species varieties and the southern limit for northern species. The Future of the Gulf Stream Although there are no definitive answers, it is believed that the Gulf Stream could be in the future or is already being impacted by global warming and the melting of glaciers.

Some studies suggest that with the melting of ice in places like Greenland, cold, dense water will flow into the ocean and disrupt the flow of the Gulf Stream and other currents that are part of the Global Conveyor Belt. If this were to happen, weather patterns worldwide could change. Recently, there has been evidence that the Gulf Stream is weakening and slowing and there is growing concern about what impacts such a change would have on the world’s climate. Some reports suggest that without the Gulf Stream, temperatures in England and northwestern Europe could drop by 4-6°C. These are the most dramatic of the predictions for the future of the Gulf Stream but they, as well as today’s climate patterns surrounding the current, show its importance to life in many places around the world. An Overview of Ocean Currents and How They Circulate Share By Amanda Briney Ocean currents are the vertical or horizontal movement of both surface and deep water throughout the world’s oceans. Currents normally move in a specific direction and aid significantly in the circulation of the Earth’s moisture, the resultant weather, and water pollution. Oceanic currents are found all over the globe and vary in size, importance, and strength.

Some of the more prominent currents include the California and Humboldt Currents in the Pacific , the Gulf Stream and Labrador Current in the Atlantic , and the Indian Monsoon Current in the Indian Ocean . These are just a sampling of the seventeen major surface currents found in the world’s oceans. The Types and Causes of Ocean Currents In addition to their varying size and strength, ocean currents differ in type. They can be either surface or deep water. Surface currents are those found in the upper 400 meters (1,300 feet) of the ocean and make up about 10% of all the water in the ocean. continue reading below our video 4 Tips for Improving Test Performance Surface currents are mostly caused by the wind because it creates friction as it moves over the water. This friction then forces the water to move in a spiral pattern, creating gyres. In the northern hemisphere, gyres move clockwise; while in the southern hemisphere, they spin counterclockwise. The speed of surface currents is greatest closer to the ocean’s surface and decreases at about 100 meters (328 ft) below the surface.

Because surface currents travel over long distances, the Coriolis force also plays a role in their movement and deflects them, further aiding in the creation of their circular pattern. Finally, gravity plays a role in the movement of surface currents because the top of the ocean is uneven. Mounds in the water form in areas where the water meets land, where water is warmer, or where two currents converge. Gravity then pushes this water down slope on the mounds and creates currents. Deep water currents, also called thermohaline circulation, are found below 400 meters and make up about 90% of the ocean. Like surface currents, gravity plays a role in the creation of deep water currents but these are mainly caused by density differences in the water. Density differences are a function of temperature and salinity. Warm water holds less salt than cold water so it is less dense and rises toward the surface while cold, salt laden water sinks. As the warm water rises, the cold water is forced to rise through upwelling and fill the void left by the warm.

By contrast, when the cold water rises, it too leaves a void and the rising warm water is then forced, through downwelling, to descend and fill this empty space, creating thermohaline circulation. Thermohaline circulation is known as the Global Conveyor Belt because its circulation of warm and cold water acts as a submarine river and moves water throughout the ocean. Finally, seafloor topography and the shape of the ocean’s basins impact both surface and deep water currents as they restrict areas where water can move and "funnel" it into another. The Importance of Ocean Currents Because ocean currents circulate water worldwide, they have a significant impact on the movement of energy and moisture between the oceans and the atmosphere. As a result, they are important to the world’s weather. The Gulf Stream, for example, is a warm current that originates in the Gulf of Mexico and moves north toward Europe. Since it is full of warm water, the sea surface temperatures are warm, which keeps places like Europe warmer than other areas at similar latitudes. The Humboldt Current is another example of a current that affects weather.

When this cold current is normally present off the coast of Chile and Peru, it creates extremely productive waters and keeps the coast cool and northern Chile arid. However, when it becomes disrupted, Chile’s climate is altered and it is believed that El Niño plays a role in its disturbance. Like the movement of energy and moisture, debris can also get trapped and moved around the world via currents. This can be man-made which is significant to the formation of trash islands or natural such as icebergs. The Labrador Current, which flows south out of the Arctic Ocean along the coasts of Newfoundland and Nova Scotia, is famous for moving icebergs into shipping lanes in the North Atlantic. Currents plan an important role in navigation as well. In addition to being able to avoid trash and icebergs, knowledge of currents is essential to the reduction of shipping costs and fuel consumption. Today, shipping companies and even sailing races often use currents to reduce time spent at sea. Finally, ocean currents are important to the distribution of the world’s sea life. Many species rely on currents to move them from one location to another whether it is for breeding or just simple movement over large areas.

Ocean Currents as Alternative Energy Today, ocean currents are also gaining significance as a possible form of alternative energy. Because water is dense, it carries an enormous amount of energy that could possibly be captured and converted into a usable form through the use of water turbines. Currently, this is an experimental technology being tested by the United States, Japan, China, and some European Union countries. Whether ocean currents are used as alternative energy, to reduce shipping costs, or in their natural to state to move species and weather worldwide, they are significant to geographers, meteorologists, and other scientists because they have a tremendous impact on the globe and earth-atmosphere relations. Watch a narrated slideshow about ocean currents and their global impact from the National Oceanic and Atmospheric Administration. Ocean Circulations | Climate Education Modules for K-12 Ocean Circulations body Ocean circulations are very complex and can travel in different directions depending on how deep you look in the ocean, but the main source that drives all ocean circulations is the energy from the sun. Two important by-products of the sun’s energy that affect circulation are wind and ocean density. How does wind affect ocean circulation? Figure A: Ocean Currents Surface ocean currents are primarily affected by wind patterns.

Trade winds can push water along the top of the ocean and aid in the formation of surface currents. One example of a wind-driven circulation affecting an ocean current is the Gulf Stream. The Gulf Stream takes very warm water from the Gulf of Mexico and parts of the Caribbean Sea and transports it northward. During the winter, the Gulf Stream can have a great effect on storm systems along the East Coast of the United States. For example, nor’easters can strengthen and grow over the Gulf Stream and bring heavy snow or rain, strong winds, and damaging beach erosion to the East Coast. It used to be thought that the flow of the Gulf Stream alone helped keep Europe warm in winter, but it has been recently shown that the temperate climate of Great Britain comes from warm air moving along with the Gulf Stream over the Atlantic Ocean. This keeps temperatures along the western coast of Europe milder than continental areas farther east away from the coast. Figure B: The Flow of the Gulf Stream Image from the NC State Climate Office How does ocean density affect ocean circulation? Deep ocean currents are primarily driven by ocean density. In order to understand how density can affect ocean circulation, we need to understand what density is.

Density for salt water depends on two things: temperature and salinity (how salty the water is). A more common name for this kind of circulation is known as a thermohaline circulation. In Greek, “thermos” stands for heat, while “haline” means salinity (the amount of salt in water). Although warmer ocean water near the surface of the ocean is less dense and contains less salt than colder, deeper ocean water, warm water actually is capable of holding more salt than cold water. So why is the deeper, colder water saltier than the warmer, surface-based seawater? One answer: It is due to freshwater runoff. At the ocean’s surface, fresh water from rivers or precipitation falling from the sky mixes with the ocean water and dilutes it. As a result, the water at the ocean surface is less salty than the water below it. Another answer: formation of ice at high latitudes. In the northern Atlantic and Pacific Oceans, when the air gets cold enough for ice to form on the surface of the ocean, the dissolved salt is excluded from the ice that forms, leading to cold and extra salty water forming at these latitudes as the fresh water becomes ice.

This very dense water sinks to deep levels in the ocean and spreads out from there. The bottom topography of the ocean and the arrangement of the continents helps steer this deep salty water around the globe. From this, we can get underwater currents that can be thousands of feet below the surface of the ocean. In a way, the thermohaline circulation can work together with wind-driven circulations and create a conveyer belt that circulates all around the world. Thus, the combined thermohaline circulation and wind-driven circulation has also been dubbed the ‘Great Ocean Conveyor Belt'. Figure C: The Conveyor Belt Image from NOAA Ocean Currents relation to health How does this relate to public health? Increasing carbon dioxide levels in waters and warmer water temperatures impact global ocean circulations, which are one of the primary drivers of weather, temperature, precipitation, and seasons, and therefore affect a variety of aspects of health.1,2 Figure D: The additional carbon dioxide being absorbed by the oceans impact the ocean circulations and currents that drive weather, temperature, precipitation, and seasons. Image from EPA 1Climate Institute. Oceans and sea level rise: Consequences of climate change on the oceans, thermohaline circulation.

<#thermohaline> Accessed December 6, 2012. 2National Oceanic and Atmospheric Association, PMEL Carbon Program. Ocean carbon uptake. < Accessed November 23, 2012. The Source of Europe's Mild Climate » American Scientist FEATURE ARTICLE The Source of Europe's Mild Climate The notion that the Gulf Stream is responsible for keeping Europe anomalously warm turns out to be a myth Richard Seager If you grow up in England, as I did, a few items of unquestioned wisdom are passed down to you from the preceding generation. Along with stories of a plucky island race with a glorious past and the benefits of drinking unbelievable quantities of milky tea, you will be told that England is blessed with its pleasant climate courtesy of the Gulf Stream, that huge current of warm water that flows northeast across the Atlantic from its source in the Gulf of Mexico. That the Gulf Stream is responsible for Europe's mild winters is widely known and accepted, but, as I will show, it is nothing more than the earth-science equivalent of an urban legend. This is not to say that there is no climatological mystery to be explained.

The countries of northern Europe do indeed have curiously mild climates, a phenomenon I didn't really appreciate until I moved from Liverpool to New York. I arrived in the Big Apple just before a late-summer heat wave, at a time when the temperature soared to around 35 degrees Celsius. I had never endured such blistering temperatures. And just a few months later I was awestruck by the sensation of my nostrils freezing when I went outside. Nothing like that happens in England, where the average January is 15 to 20 degrees warmer than what prevails at the same latitude in eastern North America. So what keeps my former home so balmy in the winter? And why do so many people credit the Gulf Stream? Like many other myths, this one rests on a strand of truth. The Gulf Stream carries with it considerable heat when it flows out from the Gulf of Mexico and then north along the East Coast before departing U.S. waters at Cape Hatteras and heading northeast toward Europe. All along the way, it warms the overlying atmosphere. In the seas between Norway and Newfoundland, the current has lost so much of its heat, and the water has become so salty (through evaporation), that it is dense enough to sink.

The return flow occurs at the bottom of the North Atlantic, also along the eastern flank of North America. This overturning is frequently referred to as the North Atlantic thermohaline circulation, or simply the "Atlantic conveyor." It is part of the global pattern of ocean circulation, which is driven by winds and the exchange of heat and water vapor at the sea surface. The Gulf Stream indeed contributes to Europe's warmth, but it is wrong to conflate the climate difference across the North Atlantic with the northward flow of warm water in the Gulf Stream. This erroneous logic leads to such statements as (from The Times of London): "The British Isles lie on the same latitude as Labrador on the East Coast of Canada, and are protected from a similarly icy climate by the Atlantic conveyor belt." Such claims are absolutely wrong. The statements scientists make about Atlantic thermohaline circulation typically read more like this one from my Columbia University colleague, Wallace S. Broecker: One of the major elements of today's ocean system is a conveyor-like circulation that delivers an enormous amount of tropical heat to the northern Atlantic. During winter, this heat is released to the overlying eastward air masses, thereby greatly ameliorating winter temperatures in northern Europe.

This assertion has the benefit of being both correct and misleading. Because it does not specify what European climate is ameliorated relative to (the climate of eastern North America?), it leaves unchallenged the incorrect version expounded in the popular media—thus contributing to the erroneous beliefs of millions. The idea that the Gulf Stream is responsible for Europe's mild winters seems to have originated with Matthew Fontaine Maury, an American naval officer who in 1855 published The Physical Geography of the Sea, which is often considered the first textbook of physical oceanography. The book was a huge success, went through many printings and was translated into three languages. The role of the Gulf Stream in shaping climate is a recurring theme in Maury's book. For example, he stated: One of the benign offices of the Gulf Stream is to convey heat from the Gulf of Mexico, where otherwise it would be excessive, and to disperse it in regions beyond the Atlantic for the amelioration of the climates of the British Isles and of all Western Europe.

According to Maury, if this transport of heat did not take place, "… the soft climates of both France and England would be as that of Labrador, severe in the extreme, and ice bound." Despite the differences in language and style, the modern statements clearly owe their provenance to this 1855 treatise. Maury thought that God set the ocean up to work this way apparently as part of His design to keep Europe warm (for unspecified reasons). But holding such religious beliefs did not stop Maury from also providing a scientific explanation for the Gulf Stream. His idea was that it was the oceanic equivalent of what in the atmosphere is known as a Hadley cell, a convection cell wherein warm air flows upward and poleward, and cold material flows downward and equatorward. In the ocean, heated surface waters take a northeastward route, in Maury's view, because of the need to conserve angular momentum as they move north and, hence, closer to the axis of the Earth's rotation. Maury did not recognize that winds drive ocean currents.

And it was not until a century later that a valid explanation of the Gulf Stream emerged: In the jargon of oceanographers, it is a westward-intensified boundary current within a subtropical gyre (a large circular current system) driven by the trade winds, which blow from east to west in the tropics, and mid-latitude westerlies, which move in the opposite direction. NWS JetStream - Ocean Circulations NWS JetStream myForecast Ocean Circulations In January 1992, a container ship near the International Date Line, headed to Tacoma, Washington from Hong Kong, lost 12 containers during severe storm conditions. One of these containers held a shipment of 29,000 bathtub toys. Ten months later, the first of these plastic toys began to wash up onto the coast of Alaska. Driven by the wind and ocean currents, these toys continue to wash ashore during the next several years and some even drifted into the Atlantic Ocean. The ultimate reason for the world's surface ocean currents is the sun. The heating of the earth by the sun has produced semi-permanent pressure centers near the surface.

When wind blows over the ocean around these pressure centers, surface waves are generated by transferring some of the wind's energy, in the form of momentum, from the air to the water. This constant push on the surface of the ocean is the force that forms the surface currents. Learning Lesson: How it is Currently Done Basic currents off the coasts of the continents. Around the world, there are some similarities in the currents. For example, along the west coasts of the continents, the currents flow toward the equator in both hemispheres. Basic currents off the coasts of the continents These are called cold currents as they bring cool water from the polar regions into the tropical regions. The cold current off the west coast of the United States is called the California Current. Likewise, the opposite is true as well. Along the east coasts of the continents, the currents flow from the equator toward the poles. There are called warm current as they bring the warm tropical water north. The Gulf Stream, off the southeast United States coast, is one of the strongest currents known anywhere in the world, with water speeds up to 3 mph (5 kph ). These currents have a huge impact on the long-term weather a location experiences.

The overall climate of Norway and the British Isle is about 18 °F (10 °C ) warmer in the winter than other cites located at the same latitude due to the Gulf Stream. Take it to the MAX! Keeping Current While ocean currents are shallow level circulations, there is global circulation which extends to the depths of the sea called the Great Ocean Conveyor. Also called the thermohaline circulation, it is driven by differences in the density of the sea water which is controlled by temperature (thermal) and salinity (haline). In the northern Atlantic Ocean, as water flows north it cools considerably increasing its density. As it cools to the freezing point, sea ice forms with the "salts" extracted from the frozen water making the water below more dense. The very salty water sinks to the ocean floor. Learning Lesson: That Sinking Feeling It is not static, but a slowly southward flowing current. The route of the deep water flow is through the Atlantic Basin around South Africa and into the Indian Ocean and on past Australia into the Pacific Ocean Basin. The Great Ocean Conveyor Belt - The blue color represents the deep cold and saltier water current with the red color indication shallower and warmer current.

If the water is sinking in the North Atlantic Ocean then it must rise somewhere else. This upwelling is relatively widespread. However, water samples taken around the world indicate that most of the upwelling takes place in the North Pacific Ocean. It is estimated that once the water sinks in the North Atlantic Ocean that it takes 1,000-1,200 years before that deep, salty bottom water rises back to the upper levels of the ocean again. The Great Ocean Conveyor Belt - The blue color represents the deep cold and saltier water current with the red color indication shallower and warmer current.

Question: What ocean current brings warm water from the Gulf of Mexico to Europe?
Answer: Gulf Stream