The depth of illumination in a water body can be measured with a

The depth of illumination in a water body can be measured with a secchi disc. A secchi disc is a simple tool used to measure water transparency or turbidity in a water body. It consists of a circular disc that is divided into quadrants and painted in alternating black and white colors. The disc is lowered into the water until it can no longer be seen, and the depth at which it disappears from view is recorded. This depth is known as the secchi depth and is used to determine the transparency of the water. The deeper the secchi depth, the clearer the water, and the shallower the secchi depth, the more turbid or cloudy the water. A photometer is a device used to measure the intensity of light, a hydrometer is used to measure the density of liquids, and an anemometer is used to measure wind speed.