A form of motion found in the near-surface water of lakes and oceans under windy conditions. When the wind is stronger than 5–8 m/s (10–15 knots), streaks of bubbles, seaweed, or flotsam form lines running roughly parallel to the wind, called windrows. Windrows are seen at one time or another on all bodies of water, from ponds to oceans. In the 1920s, Irving Langmuir hypothesized that they are produced by convergences in the water rather than by a direct action of the wind. Langmuir proposed that as the surface water is blown downwind it moves in a spiral fashion, first angling toward the streaks along the surface, next sinking to some depth, then diverging out from under the streaks, and finally rising again in between the streaks (see illus.). In a series of observations and experiments conducted in the North Atlantic and on Lake George in New York, he was able to confirm this basic form of the circulation.