As someone who has sailed, flew over and studied the North Atlantic, from the
Equator to the Arctic Circle, for more years than I care to say, Paul's
explanation of the Trade Winds was close but not quite right. The Trade Winds
properly the Northeast Trade Winds begin near the Canary Islands, they are those
winds out of Northeast and East-Northeast on the South side of the
semi-permanent Atlantic Anticyclone (High Pressure) that is generally centered mid
Atlantic. The Bermuda High is a westward extension of it. The Trades are generally
stronger in winter and lighter in summer.
North of the Trades is a belt of calms or light and variable winds known as
the Horse Latitudes about 5 degrees of latitude in width near 30 North but
moves North-South about 5 degrees with the migration of the sun. At times this can
extend from Cape Hatteras to North Africa. For reference the Canaries are
centered near 28N 16W. The winds north of the Horse Latitudes are generally from
the West (southwest to northwest) and are known as the Westerlies.

Just as important as the winds is the great river of water (The North
Atlantic Gyre), driven by the winds, that flows around the High and consists mainly
of four currents the North Equatorial Current, the Gulf Stream, the North
Atlantic Current and the Canaries Current. The speed on the southside in the North
Equatorial Current is about 1/2 to 1 mph out of the East, the Gulf Stream has
an average speed of 4 mph. Looking at a map of the Gulf Stream and the North
Atlantic Current it's like an arrow pointed from off the Virginia Capes
northeast toward Great Britain then splits west of Ireland with part flowing north
toward Iceland and Norway, the North Atlantic Drift,  (this is what makes Great
Britain, Iceland and Northeastern Europe livable) and part flowing south into
the Canaries Current. Supposedly you could throw a bottle into the ocean in
Bahamas and have it return years later having made a complete circle.

Iceland is not under the influence of the Atlantic Anticyclone but the
Icelandic Low, and that portion of the Gulf Stream turning north and warms southern
Iceland.

Ref: Explanations and Sailing Directions by Matthew F. Maury 1858
NASA-Ocean Currents
The History of the Gulf Stream

Clay Gullatt, Senior Chief USN Ret.
former Hurricane Hunter, Meteorologist Commander Second Fleet,
Operations Chief Fleet Weather Central Norfolk,
Radar Ops North Atlantic Barrier

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