A small disturbance of wind in a large wind flow, which can produce turbulent conditions or turbulence. They can also be areas of warmer air north of the main westerlies or colder air south of the westerlies. (See cut-off high or cut-off low.) In oceanic circulation, it is a circular movement of water usually formed where currents pass obstructions, between two adjacent currents flowing counter to each other, or along the edge of a permanent current.