Gulf Stream

Gulf Stream, warm current of the North Atlantic Ocean, flowing in a generally north-eastern direction from the Straits of Florida to the Grand Banks, east and south of Newfoundland Island. The term is often extended to include the North Atlantic Drift, which flows from the Grand Banks to the shores of western Europe, Scandinavia, and the eastern islands of the Arctic Ocean. The Gulf Stream is of great climatological importance because of its moderating effects on the climate of western Europe.

The sources of the Gulf Stream are the two equatorial currents: the North Equatorial Current, which flows west, roughly along the tropic of Cancer; and the South Equatorial Current, which flows from the coasts of south-western Africa to South America and then north into the Caribbean. The fusion of these two warm currents and a certain amount of water from the Gulf of Mexico forms the Gulf Stream.

In the straits that separate Florida from the Bahamas and Cuba, the Gulf Stream has a maximum width of about 80 km (50 mi) and a depth of about 640 m (2,100 ft). The surface temperature is about 25° C (77° F). It is the strongest current in the North Atlantic and the surface current averages about 5 km/hr (3 mph). Further north the stream gradually widens and is approximately 480 km (300 mi) wide off New York. Between the stream and the north-eastern coast of the United States lies an area of colder water, sometimes called the Cold Wall.

South of the Grand Banks, the stream meets and mixes with the cold Labrador Current, forming numerous whirlpools. From this point the stream, or properly the North Atlantic Drift, moves north-east across the ocean, driven at a rate of less than 8 km (5 mi) per day by the prevailing south-western winds. The drift then splits into several branches, of which the most important are the central flow, which reaches the coasts of Europe and then turns north; a northern tongue, the Irminger Current, which reaches the southern and western shores of Iceland; and a southern tongue, which first flows past the Azores and then past the Canary Islands.

All the way north from its source to the region of the Grand Banks, the Gulf Stream has special physical characteristics, including a markedly bright blue colour and a high salinity. After the Gulf Stream mixes with the Labrador Current, the characteristic colour is lost, but the water of the North Atlantic Drift remains markedly salty.

The water volume of the Gulf Stream is estimated to be about 65 times greater than that of all the world’s rivers combined, or 300 times greater than that of the Amazon, the world’s largest river. Not only does the Gulf Stream transport massive amounts of water, but it also moves tremendous amounts of heat from the tropics into the temperate latitudes. It is responsible for the formation of tropical coral reefs as far north as Bermuda and for keeping western Europe mild and ice-free.