gyre

Merriam-Webster's Word of the Day for November 13, 2011 is:

gyre • \JYRE\  • noun
: a circular or spiral motion or form; especially : a giant circular oceanic surface current

Examples:
Sophia will be focusing her graduate studies on the effects of ocean gyres on North America's climate.

"When gyres of warm wind coming over the Pacific hit the cold water in the Bay, the air chills and condenses to form fog." -- From an article by Lily Dayton in the Monterey County Herald (California), July 26, 2011

Did you know?
William Butler Yeats opens his 1920 poem, "The Second Coming," with the following lines: "Turning and turning in the widening gyre / The falcon cannot hear the falconer; / Things fall apart; the center cannot hold; / Mere anarchy is loosed upon the world…." Often found in poetic or literary contexts as an alternative to the more familiar "circle" or "spiral," "gyre" comes via the Latin "gyrus" from the Greek "gyros," meaning "ring" or "circle." Today, "gyre" is most frequently encountered as an oceanographic term that refers to vast circular systems of ocean currents, such as the North Atlantic Gyre, a system of currents circling clockwise between Europe, Africa, and the Americas. "Gyre" is also sometimes used of more localized vortices such as those produced by whirlpools or tornados.