Downwelling

Part of speech: noun

Definitions

1. Water or air moving downward from the surface due to density increase, convergence, or cooling effects
2. The process by which denser surface material sinks vertically into deeper layers of a fluid environment
3. The sinking of surface water or air toward greater depths or lower altitudes due to increased density, cooling, or convergence
4. A process in which lighter surface fluids move downward through denser layers in aquatic or atmospheric systems

Etymology: "Downwelling" is a compound of "down" and "welling," the present participle of "well," used as a noun. "Well" in the sense of a spring or fountain, and "welling" in the sense of water rising up out of the ground, are old English words, so the compound puts a sinking motion onto a root that normally describes things coming up. In oceanography, the term names the process in which surface water sinks below the layers beneath it, usually where waters become denser through cooling or evaporation, or where converging currents push water downward. It is the opposite motion of upwelling, which brings cold, nutrient-rich water toward the surface. The pairing shows how the prefix "down-" can be attached to a verb of rising to create a precise technical contrast.

Synonyms: infiltration, descent, sinking, flowing down, current