### Richardson number

**(Ri)**
(measure of fluid stability consisting of ratio of buoyancy and shear)

The **Richardson number** (**Ri**) is a dimensionless number offering
a measure of a fluid's (e.g., atmosphere's) chances of the
Kelvin-Helmholtz instability. It is a ratio of buoyancy (in terms of density
and gravity) with shear, flow normal to the gravitational
force.

The *Richardson number* is used in meteorology and oceanography and
is applicable to some other situations when there is a chance
of the fluids mixing.

(*fluid dynamics,atmosphere*)
http://en.wikipedia.org/wiki/Richardson_number

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