June 5, 2000

The Gulf Stream is a warm ocean current in the North Atlantic Ocean, flowing from the Gulf of Mexico, northeast along the US coast to Nantucket Island, and from there to the British Isles and the Norwegian Seas.

First described by the Spanish navigator and explorer Juan Ponce de León early in the 16th century, the Gulf Stream's course was originally charted in 1770, a collaboration of Benjamin Franklin and Timothy Folger. In 1844, systematic surveying of the stream was undertaken by the United States Coast and Geodetic Survey. More recent efforts occurred in the early 1930's, by the ketch Atlantis of the Woods Hole Oceanographic Institution.

The Gulf of Mexico, once thought to be the source of the Stream, actually contributes very little to its flow. The Gulf Stream results when two strong currents, the North and South Equatorial Currents, mingle in the passage between the Windward Islands and the Caribbean Sea. Off the southern coast of Florida, it is strengthened by other currents from the northern coast of Puerto Rico and from the Bahamas to the east.

The true Gulf Stream flows between the Straits of Florida, and the Grand Banks. However, it is part of a much larger Gulf Stream System, that covers the entire northward and eastward flow from the Straits of Florida, including the branches crossing the North Atlantic from the region south of the Newfoundland Banks.

About 1,500 miles (2,414 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.

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.

A major contribution of the Gulf Stream System is its warming effect upon the climates of adjacent land areas. In winter, the air over the ocean west of Norway is more than 40° F (22° C) warmer than the average for that latitude, one of the greatest temperature anomalies in the world. The prevailing westerly winds carry the warmth and moisture of the ocean to northwestern Europe, giving Bergen, Norway, at 60 degrees north latitude, an average high temperature for its coldest month of 34° F (1° C), while Reykjavík, Iceland, 4 degrees of latitude farther north, has a 31° F (-0.6° C) average for its coldest month.

Interestingly, along the western North Atlantic, where the winds are predominantly from the shore, the Gulf Stream has little effect. Halifax, Nova Scotia, nearly 1,000 miles (1,609 km) south of Bergen, averages only 23° F (-5° C) during its coldest month.

In southwestern England, the climatic modification produced by the current is reflected in the extraordinary mildness of the winters at this northern latitude. Here, winter vegetables and flowers are grown, and lemon trees are seen in southern Devonshire.

And, let's not forget the palm trees in Scotland!!

Logan Botanic Garden is in the parish of Kirkmaiden, in the Rhinns of Galloway, a narrow peninsula that juts out into the Irish Sea, at the extreme south-west of Scotland.

Our friend, the Gulf Stream, gives these gardens a virtual sub- tropical climate. Thus, the Logan features plants usually identified with warmer areas of the world, including palm trees.

What a different world this would have been, absent the Gulf Stream, with the British Isles and Norway occupying a frozen tundra!