Spray in the atmospheric surface layer: Laboratory study

A laser and phototransistor unit has been developed to measure spray produced in a laboratory wind wave tank. Under a given wind velocity, the droplet concentration is found to decrease in a power law form with the elevation above mean water surface; the exponent varies inversely with the friction velocity of the wind. At a given elevation, the droplet concentration increases exponentially with the wind velocity, and the spray at a higher elevation above the water surface initiates at a greater wind velocity. The droplet-size distribution curves drop off very rapidly and similarly for diameters greater than 200 μ. The speed of the droplet approaches the wind velocity, and the spray stress is negligible in comparison with the wind stress.