The Secchi disk is a simple tool used to measure water clarity by determining the depth at which the disk is no longer visible in the water. It consists of a circular, white or black-and-white disk that is lowered into the water on a marked rope. The depth at which the disk disappears is recorded, and this measurement helps assess the transparency of the water. The clearer the water, the deeper the disk can be submerged before it becomes invisible, providing valuable information about water quality and ecological health.
Yesterday I measured Secchi disk transparency and compared that with simultaneous photometer measurements in a subtropical estuary. The lower border of the photic zone (1% of surface irradiance) according to my YSI photometer was at a depth of 4.7 m , while Secchi reading was at 1.6 m. Multiplying 1.6 by 2 gives 3.2, which is significantly lower than 4.7 m. Before that observation I believed in the "double-Secchi rule".
Serafino Secchi died in 1628.
Dante Secchi died in 1981.
Dante Secchi was born in 1910.
Niccolo Secchi has written: 'Gl'inganni comedia'
Angelo Secchi was born on 1818-06-29.
Angelo Secchi died on 1878-02-26.
Giuseppe Secchi was born on 1931-04-06.
Antonio Secchi died on June 7, 2013.
Secchi - 2013 is rated/received certificates of: Sweden:Btl
The cast of Secchi - 2013 includes: Pierfrancesco Favino as Narrator