Turbidity (redirected from Nephelometric turbidity units)

turbidity [tər′bid·əd·ē]

(analytical chemistry)

Measure of the clarity of an otherwise clear liquid by using colorimetric scales.

Cloudy or hazy appearance in a naturally clear liquid caused by a suspension of colloidal liquid droplets or fine solids.

(astronomy)

The formation of disks centered on stars in long-exposure photographs as a result of light scattering by grains in the emulsion.

(meteorology)

Any condition of the atmosphere which reduces its transparency to radiation, especially to visible radiation.

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Turbidity 

the capacity of an optically nonuniform medium to scatter light passing through it (see). The extinction coefficient is a quantitative characterization of turbidity and is given by the equation.

τ ═ (l/I) ln (I₀/I)

where I₀ and I are the intensities of a light beam before and after passage through a layer of the medium of thickness l. Turbidity is determined by methods of nephelometry and turbidimetry.