Gulf Stream

Topic: Movements of Ocean Water: Waves, Tides and Currents · NCERT: Class 11, Ch 8 "Solar Radiation, Heat Balance and Temperature"; Class 11, Ch 12 "Water (Oceans)"; Class 11, Ch 13 "Movements of Ocean Water"

Meaning

The Gulf Stream is a strong warm ocean current. It leaves the Gulf of Mexico through the Florida Strait, flows north along the US east coast, and turns north-east out to sea at Cape Hatteras towards Newfoundland. From there it crosses the Atlantic as the North Atlantic Drift.

It matters because it carries a huge amount of tropical heat towards the pole. Where it meets the cold Labrador Current off Newfoundland, it creates thick fog and one of the world's great fishing grounds.

Explanation

How it forms and moves

• Ocean current (a large, steady flow of seawater in one direction, like a river inside the ocean).
• Warm current (a current that flows from near the equator towards the poles and warms the coasts it passes). The Gulf Stream is a warm current.
• Water comes in from the east:
• The trade winds drive the North Equatorial Current from east to west across the tropical Atlantic.

• This current brings water into the Caribbean and the Gulf of Mexico.

• Water leaves through a narrow gap:

• The water flows out through the Florida Strait (between Florida and Cuba, about 24°N).

• It then runs north along the US east coast.

• It turns away from the coast:

• At Cape Hatteras (North Carolina, about 35°N) it turns north-east and flows out to sea.

• It moves towards Newfoundland (Canada).

• Why it bends right:

• The Coriolis force (the turning effect of the earth's rotation) pushes moving water to the right in the Northern Hemisphere.
• The westerly winds (winds blowing from west to east in the middle latitudes) then push the water east across the ocean.

Speed and size

• It is one of the strongest warm currents in the world.
• Average speed: about 6.4 km per hour [2].
• Fastest near the surface, usually up to about 9 km per hour [2].
• Further north it widens and slows to about 1.6 km per hour [2].
• It carries more water than all the world's rivers put together [2].

Its place in the North Atlantic gyre

• Gyre (a large ring of currents that goes round an ocean basin). In the North Atlantic the gyre turns clockwise.
• The Gulf Stream is the western side of this ring.
• The full loop, from west to east and back:

• Gulf Stream (warm, west) → North Atlantic Drift (warm, north) → Canary Current (cold, east) → North Equatorial Current (warm, south) → back to the Gulf of Mexico.

• General rule for the Atlantic: warm currents on the western side of basins (Gulf Stream, Brazil) and cold currents on the eastern side (Canary, Benguela).

What happens downstream

• Meeting the Labrador Current off Newfoundland:
• Warm, moist air over the Gulf Stream moves over the cold Labrador water.
• The air cools, its water vapour condenses, and dense fog forms. This is a major danger to ships.

• Warm and cold water mix over the Grand Banks (shallow parts of the continental shelf off Newfoundland). Nutrients spread through the water, plankton (tiny floating plants and animals) grow well, and fish such as cod are plentiful.

• Becoming the North Atlantic Drift:

• The Gulf Stream continues east and north-east across the Atlantic as the North Atlantic Drift.
• It is called a "drift" because it is a slow surface flow driven by the westerly winds.
• The westerly winds pick up its heat and moisture and carry them onto north-west Europe, so winters there are mild and wet.

Where it occurs

• Gulf of Mexico: where the water collects before it flows out.
• Florida Strait: between Florida (USA) and Cuba, about 24°N. This is where the current leaves the Gulf.
• US east coast: the current runs north along it.
• Cape Hatteras: North Carolina, about 35°N. Here the current turns north-east, away from the coast.
• Newfoundland and the Grand Banks: Canada. Here the current meets the cold Labrador Current.
• Sargasso Sea: a calm, warm area of the North Atlantic, roughly east of Bermuda. The Gulf Stream forms its western edge.
• North-west Europe (Britain, Norway): the Gulf Stream does not reach these coasts itself. It gets there as the North Atlantic Drift.
• India: the Gulf Stream does not touch India. In the Indian Ocean, INCOIS monitors the ocean, much as currents and icebergs are watched in the North Atlantic.

Don't confuse with

• North Atlantic Drift: this is the Gulf Stream's wind-driven continuation east of Newfoundland. The Drift, not the Gulf Stream itself, keeps Hammerfest, Narvik and Murmansk ice-free.
• Labrador Current: a cold current that flows south from the Arctic past Labrador and Newfoundland. The Gulf Stream is warm and flows north. The two meet off Newfoundland.
• Brazil Current: also a warm current on the western side of a basin, but in the South Atlantic. It flows south along Brazil and meets the cold Falkland Current off the Río de la Plata, not the Labrador Current.
• Canary Current: the cold current on the eastern side of the same clockwise gyre. It flows south from Spain to Senegal and makes the coastal Sahara drier.

Prelims Hooks

• The Gulf Stream leaves the Gulf of Mexico through the Florida Strait and turns away from the US coast at Cape Hatteras.
• Grand Banks (Newfoundland): the warm Gulf Stream meets the cold Labrador Current. The result is fog and a rich cod fishery.
• Order from west to east across the North Atlantic: Gulf Stream → North Atlantic Drift → Canary Current.
• The Sargasso Sea is the only sea with no land boundary. It is enclosed by the Gulf Stream (west), North Atlantic Drift (north), Canary (east) and North Equatorial (south) currents [3].
• Trap: Norway's ice-free ports are kept open by the North Atlantic Drift, not by the Gulf Stream directly.
• The Gulf Stream carries more water than all the world's rivers put together. It slows to about 1.6 km per hour further north [2].

Mains Points

• Moving heat towards the pole and shaping climate:
• The Gulf Stream and its continuation, the North Atlantic Drift, carry tropical heat to high latitudes.
• North-west Europe therefore has mild winters and ice-free ports even north of the Arctic Circle, while Labrador at the same latitude freezes.

• Isotherms (lines on a map joining places with the same temperature) bend towards the pole over the north-east Atlantic. This shows how warm currents break the normal link between latitude and temperature (GS-I).

• Fisheries and the economy (GS-III):

• Where the Gulf Stream mixes with the Labrador Current, plankton grow well. This makes the Grand Banks one of the world's great fishing grounds.

• Overfishing (the collapse of cod on the Grand Banks) and ocean warming threaten such meeting zones of warm and cold water. This links to sustainable use of resources.

• Hazards to shipping and the need for monitoring (GS-III, disasters):

• Fog where the Gulf Stream meets the Labrador Current, and icebergs carried south by the Labrador Current (the Titanic, April 1912), make the North Atlantic shipping lanes dangerous.
• This shows why ocean monitoring matters. India's INCOIS plays a similar role for the Indian Ocean.

Related concepts

• North Atlantic Drift
• Canary Current
• Sargasso Sea
• Labrador Current
• Brazil Current
• Falkland Current
• Benguela Current

Read more

• Currents of the Atlantic Ocean