Macrobubble clouds produced by breaking wind waves: A laboratory study

Clouds of large air bubbles produced by breaking wind waves have been studied in a laboratory tank. Temporal evolutions of these macrobubble clouds, including their length scales, aspect ratios, area scales, and velocities, are presented; the bubble concentration and void ratio within the cloud are also found. The initial downwind velocity of the cloud is about one half, but can reach about two thirds, the phase velocity of the breaking wave. The maximum penetrating depth of the cloud is about one half the breaking wave height. All these geometric and kinematic characteristics of the cloud are also associated with those of the breaking wave.