Right-sized particles of salt can act as moisture condensation nuclei to form or brighten clouds in air that is saturated with water vapor. Many places over oceans frequently form a layer of “marine clouds” at about 1 to 2 kilometers elevation. At such locations, it may be possible to spray ocean water into tiny drops that evaporate to leave a salt particle that is just the right size to act as condensation nuclei and thereby form or brighten such clouds. Teams at the University of Washington and Stanford University are attempting to develop this technology. Their goals and progress are described in a September2021 article.
Salt particles that do not trigger formation of water droplets are still effective to reflect (scatter) solar energy, so the former term “marine cloud brightening” has been updated to “marine sky brightening”.