Eventually, the loop breaks off and forms an eddy. The eddy has a core of warm water, and rotates clockwise as it moves west across the gulf. Clockwise-rotating eddies in the northern hemisphere are called anticyclones. Smaller eddies spin off the warm anticyclones. These rotate in the opposite direction, and are called cyclones.
Anticyclones contain few nutrients to support plant and animal life.
B. Cyclones draw cold, nutrient-rich water from the deep gulf up toward the surface. A contour map of the gulf depicts the variations in sea-surface height caused by Loop Current eddies. This map shows the Loop Current soon after it shed Eddy C in mid-September 1996. Dark purple areas indicate anticyclonic Loop Current eddies A, B, and C moving through the gulf. The Loop Current shed a series of three such anticyclonic eddies in 1996, but throughout the year a broad area of cyclonic, lower than average sea-surface height remained in the northeast corner of the gulf.