Secchi disk


noun

an opaque, white or black-and-white disk used to measure the cloudiness or turbidity of ocean water by the point at which it is no longer visible from the surface.

QUIZZES

"EVERYDAY" VS. "EVERY DAY" QUIZ: IS IT ONE WORD OR TWO?

An everyday activity is one you do every day. (Thanks, English.) Practice using "everyday," one word, and "every day," two words, in this fun quiz with … everyday example sentences!
Question 1 of 16
“Everyday" is an adjective that describes things that happen habitually or items that are normal items or events.
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Scientific definitions for secchi disk

Secchi disk

An instrument used for measuring the clarity of water, especially seawater. It consists of a circular plate divided into alternating black and white quadrants and attached to a long measuring tape. The plate is lowered into the water, and the depth at which it is no longer visible from the surface is recorded. The Secchi disk is named after its inventor, Italian astronomer Angelo Secchi (1818-1878). See also Secchi depth.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.