Turbulence (or turbulent flow)
is chaotic flow of a fluid.
It is characterized by changes in flow velocity
and pressure over space and time, and eddies,
i.e., circular or swirling flows, often lasting
only a short time.
In contrast, a laminar flow has the
fluid flowing in an organized fashion,
potentially continuously.
Turbulence in Earthatmosphere is of interest to astronomers
because it is a contributor to seeing issues, and is a target
of adaptive optics (AO).
Turbulence also is a factor within the gas of some astronomical objects
e.g., within stars or clouds: one means of detecting it is
through analysis of spectral lines.