Depending on density, phenomena named for this quantity may create structures categorized on a scale of either Ta (“T-A”) through Te (“T-E”) or S3 through S1. This quantity names a type of flow whose effects fall on the Lowe and Bouma sequences and which is the liquid analog of pyroclastic currents. Samples with nonzero values of this quantity violate the assumptions of the Beer–Lambert law due to scattering within them. This quantity can (-5[1])be inferred from the amount of light reflected by 90 degrees in a nephelometer and can be given in NTUs. (10[1])The Secchi (“SECK-ee”) disk is used in (10[2])tests of this quantity, (10[2])in which the (10[1])disk falls until one can no longer distinguish black and white quadrants. For 10 points, (10[1])name this property of fluids in which large amounts of particulate (10[1])or other matter cause cloudiness. ■END■ (10[1])