Fr.: doigts de sel
Oceanography: One of several alternating columns of rising and descending water resulting from a → mixing process that occurs when warm salty water overlies a colder and relatively fresher layer of water. If the overlying salty water loses enough heat, it sinks down into the colder, fresher water, lengthening into a finger of salty water. Becuse the finger loses heat faster than it loses salt, the salt finger will continue to sink (salty water is denser than fresh water of the same temperature). Hence the salt finger loses more heat and displaces the colder water around it, which rises up and mixes into the warm salty layer above. Salt fingers are an example of → double-diffusive convection and play an important role in oceanic mixing. See also → fingering instability, → fingering convection.