| the depth at which a Secchi disk is no longer visible from the surface of ocean water. |
Sec·chi depth  (sěk'ē)  n. A measure of the cloudiness or turbidity of surface water. [After the Secchi disk.] |
| Secchi depth (sěk'ē) Pronunciation Key
A measure of the clarity of water, especially seawater. Secchi depth is measured using a circular plate, known as a Secchi disk, which is lowered into the water until it is no longer visible. High Secchi depths indicate clear water; whereas low Secchi depths indicate cloudy or turbid water. See also Secchi disk. |