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Jacob Perkins (1766–1849) proposed a bathometer based on the compressibility of water. [4] In this instrument the movement of a piston compressing a body of water enclosed in its cylinder is dependent on the pressure of the water outside the cylinder, and hence its depth. The amount the piston moved can be measured when it is returned to the ...
Weather stations typically have these following instruments: Thermometer for measuring air and sea surface temperature; Barometer for measuring atmospheric pressure; Hygrometer for measuring humidity; Anemometer for measuring wind speed; Pyranometer for measuring solar radiation; Rain gauge for measuring liquid precipitation over a set period ...
These methods include making use of the different depths to which different frequencies of light penetrate the water. When water is clear and the seafloor is sufficiently reflective, depth can be estimated by measuring the amount of reflectance observed by a satellite and then modeling how far the light should penetrate in the known conditions.
A sailor and a man on shore, both sounding the depth with a line. Depth sounding, often simply called sounding, is measuring the depth of a body of water. Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seabed topography. Soundings were traditionally shown on nautical charts in fathoms ...
The depth at which the disk is no longer visible is taken as a measure of the transparency of the water. This measure is known as the Secchi depth and is related to water turbidity . Since its invention, the disk has also been used in a modified, smaller 20 cm (8 in) diameter, black-and-white design to measure freshwater transparency.
In the past, a common time measuring instrument was the sundial. Today, the usual measuring instruments for time are clocks and watches. For highly accurate measurement of time an atomic clock is used. Stopwatches are also used to measure time in some sports.
A bottom-mounted ADCP can measure the speed and direction of currents at equal intervals all the way to the surface. Mounted sideways on a wall or bridge piling in rivers or canals, it can measure the current profile from bank to bank. In very deep water they can be lowered on cables from the surface. The primary usage is for oceanography. [4]
Pressure in the tube is proportional to the depth (and density) of the liquid over the outlet of the tube. [3] Air bubbler systems contain no moving parts, making them suitable for measuring the level of sewage, drainage water, sewage sludge, night soil, or water with large quantities of suspended solids. The only part of the sensor that ...