An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A deviation in the steady flow of a fluid causing a vortex-like motion running contrary to the general flow.
Meteo.: A small disturbance of wind in a large wind flow, which can produce turbulent conditions or turbulence.

Late M.E., from O.E. ed- "turning" + ea "water;" akin to O.N. itha.

Gižâv, from dialectical Kurd. "whirlpool," from giž "turning," Pers. gij "giddy-headed, vertigio;" Laki géž "whirlpool," vagéža "whirlwind" + âv, variant âb "water" (Mid.Pers. âb "water;" O.Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook").

An induced current circulating in masses of metal moving in a magnetic field or located in a changing magnetic field. Also known as → Foucault current.

→ eddy; → current.

A macroscopic process that occurs in a → fluid because of the relative motions induced by the non-uniform → turbulent motions of the fluid. Also known as turbulent → diffusion. Eddy diffusion may occur in an atmosphere if it is unstable against turbulence. It dominates the atmosphere below the homopause. See also → molecular diffusion.

→ eddy; → diffusion.