Figure 10.12 Shape of constant-pressure surfaces pi and the interface between two water masses of density r1, r2 if the upper is rotating faster than the lower. Left: Anticyclonic motion, warm-core eddy. Right: Cyclonic, cold-core eddy. Note that the sea surface p0 slopes up toward the center of the warm-core ring, and the constant-density surfaces slope down toward the center. From Defant (1929).