a circular disk measuring approximately 20 cm in diameter which is used to measure the abundance of plankton in water.
a black-and-white disk used to measure the clarity of water. The disk is lowered into the water until it cannot be seen and then the depth of the disk is measured. Septic system: a system that treats and disposes of household wastewater under the ground.
A Secchi disk is a black and white metal disk that is used to measure the transparency or clarity of water. The disk is lowered into the water until it is no longer visible, this is referred to as the Secchi depth and is used to determine the clarity of the water.
a black and white circle, weighted so that it can be lowered into the water by a string
a circular metal plate attached to a calibrated rope
a circular plate divided into quarters painted alternately black and white
a device used to determine water clarity
a standard way to measure visibility in water
a weighted disk painted with alternating quarters of black and white
A disk with a 4-6 inch radius that is divided into 4 equal quadrates of alternating black and white colors. It is lowered in to a section of shaded water until it can no longer be seen and then lifted back up until it can be seen once again. Averaging the two depths gives the clarity of the water.
An 8-inch diameter plate (usually all-white or with alternating black and white quadrants) used to measure transparency. Attached to a length-calibrated cord, the disk is lowered into the lake until it disappears. It is then raised until it becomes visible. The average of these depths is the Secchi disk reading. About 30 citizen lake monitors regularly collect Secchi disk readings as part of the Eagan citizen lake monitoring program. Invented by an astrophysicist and scientific advisor to the Pope, the first disk was lowered into the Mediterranean Sea by Fr. Pietro Angelo Secchi on April 20, 1865.
a circular black and white disk used for measuring turbidity
A device measuring the depth of light penetration in water.
A black and white, circular, weighted disk used to measure turbidity.
A device for measuring water clarity. A Secchi disk (named after its inventor) is a white circle (usually eight inches in diameter) with a black pattern and attached to a rope. The Secchi disk is lowered into water until the pattern is no longer visible. The depth at which this occurs is called the Secchi depth and is a measure of water clarity. Water clarity decreases as turbidity increases.
A disk used to measure the visibility of water.
a simple device for measuring turbidity.
Instrument used by scientists to measure water clarity. The depth at which the disk’s black and white marks cannot be seen is called the “secchi depth.
A 20cm reflective disk used by volunteers and professional researchers to determine water clarity and derive a value used in computing a lake’s trophic status.
A black and white disk, usually 20 cm. in diameter. Measures the clarity of the water.
A small (20 cm) disk which is used to measure the transparency of water. It is lowered into the water until it is no longer visible.
A white disk of 20–30 cm diameter used to measure clarity of water. The Secchi depth is the depth at which the disk disappears from view.
Created in 1865 by Pietro Angelo Secchi, the Secchi disk is a device used to measure water transparency in open waters of lakes, bays, and the ocean. The pattern shown in the image is drawn or painted onto a card or acrylic, mounted on a pole or line, and lowered slowly down in the water. The depth at which the pattern on the disk is no longer visible is taken as a measure of the transparency of the water.