The Secchi disk, invented in 1865 by Angelo Secchi - the Pope's astronomer - is a circular disk that is used to measure water transparency in oceans and lakes. kaver's diary
The concept had long been used as a navigational tool by sailors. By lowering a dinner plate beneath the waves and measuring the depth it disappeared, it provided the crew with an indication of what ocean current they were currently sailing through.vieerli123
Fr Secchi was asked by the head of the Papal Navy to measure the transparency in the Mediterranean Sea. This task gave rise to the formalised measuring system.夏日的星空
Ever since the first measurement was taken aboard the Papal yacht in April 1865, marine biologists have used it to measure phytoplankton abundance.落ち葉の色
Since Secchi's first design, there have been a number of subsequent revisions. The two most common colour variations in use today are the all-white disk and the black-and-white quadrant version.
ffing 的日誌
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