Identify the term for shallow, wind-driven circulation of water in horizontal spiral bands.

• A. Surface Current
• B. Langmuir Circulation
• C. Transverse Current
• D. Undercurrent

Answer: (B)

Langmuir circulation describes a shallow, wind-driven pattern of horizontal, spiral-like flow in the upper ocean. When wind acts on the sea surface, waves create a Stokes drift that interacts with wind shear to generate a pair of counter-rotating vortices aligned with the wind. This sets up surface convergence in narrow bands that run along the wind direction, causing surface water to pile up and sink there, while water from below upwells between the bands. The result is a repeating pattern of tight, spiral circulations in the upper layers, often visible as foam or slick lines aligned with the wind. This specific, wind-driven, upper-layer circulation is what Langmuir circulation refers to.