Salter et al. (2008) describe using unmanned, remote-controlled, wind-driven vessels (Flettner rotor ships) that would spray micron-sized drops of seawater into the air under marine clouds in order to increase their albedo. When the sprayed seawater droplets evaporate, leftover dried aerosol residues/particles (salt, biological material, etc. that was dissolved or suspended in the water droplets) will be carried by the wind up to the cloud layer where they will act as cloud condensation nuclei. Cloud condensation nuclei or cloud seeds are small particles that help form water droplets in clouds (water vapor condenses on these particles).