The photograph (below) shows the surface signature of Langmuir Circulations on Rodeo Lagoon in Marin County, California at 1400 LDT 29 May 1994. The circulations are characterized by long rolls of overturning water directed along wind; they are described in detail in the review article of Leibovich (1983). The surface signature shown in the photograph appears as windrows of bubbles, oriented approximately along the wind direction. Bubbles tend to collect at regions of convergence and down-welling from the surface. Upwelling regions with surface divergence are swept clear of bubbles. Upon close examination, the figure also reveals the waves, which are running approximately down-wind along the rows of bubbles. Neither the wind speed nor the exact wind direction were recorded. According to the September, 1993 bathymetric survey by Zembsch (1993), Rodeo Lagoon has a remarkably constant depth of 1.4 m with a bottom characterized by a layer of dark, non-cohesive organic sediment overlaying silt. That portion of Rodeo Lagoon shown in the photograph has a width of approximately 200 m.

The author thanks S. Leibovich of Cornell University and J. Howell and D. Fong of the Golden Gate National Recreation Area for helpful discussions. Special thanks to Steve, Kelly and Ulises for the hike.