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(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.
The formation of disks centered on stars in long-exposure photographs as a result of light scattering by grains in the emulsion.
Any condition of the atmosphere which reduces its transparency to radiation, especially to visible radiation.



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.

References in periodicals archive ?
The pH was adjusted with 1 N NaOH (sodium hydroxide) to the desired test pH and the turbidity adjusted according to the desired test turbidity of 30 nephelometric turbidity units (NTU) using an AC fine dust.
Using distilled water, researchers prepared 1-liter suspensions of bentonite, kaolinite, and illite (typical clays of tropical regions) with turbidities of 50, 100, and 200 nephelometric turbidity units (NTU).
Yet, the Department of Ecology is requiring in the project 401 permit that the Port of Seattle demonstrate a daily average of no more than 5 nephelometric turbidity units (NTU) in its discharge to receiving streams during the massive embankment construction.
Limits are set at five Nephelometric Turbidity Units (NTUs) above background - background being the section upstream not yet affected by dredging operations.