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Secchi Disc
The Secchi disk (or Secchi disc), as created in 1865 by Angelo Secchi, is a plain white, circular disk in diameter used to measure water transparency or turbidity in bodies of water. The disc is mounted on a pole or line, and lowered slowly down in the water. 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 diameter, black and white design to measure freshwater transparency. Similar disks, with a black-and-yellow pattern, are used as fiducial markers on vehicles in crash tests, crash-test dummies, and other kinetic experiments. History The original Secchi disk was a plain white disk and was used in the Mediterranean Sea. Today, a plain white, diameter Secchi disk remains the standard design used in marine studies. In 1899 George C. Whipple modified the original all-white S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secchi Disk Pattern
Secchi may refer to: People with the surname * Angelo Secchi, Italian astronomer * Giuseppe Secchi (1931–2018), Italian footballer * Luciano Secchi (born 1939), Italian comic book writer and publisher * Luigi Secchi (1853-1921), Italian sculptor * Marco Secchi, Italian photographer * Serafino Secchi (died 1628), Italian clergyman Other uses * Secchi (lunar crater) * Secchi (Martian crater) * Secchi depth, a measure of turbidity * Secchi disk The Secchi disk (or Secchi disc), as created in 1865 by Angelo Secchi, is a plain white, circular disk in diameter used to measure water transparency or turbidity in bodies of water. The disc is mounted on a pole or line, and lowered slowly down ..., an instrument used to measure turbidity * SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation), an instrument package on each of the STEREO spacecraft {{disambig, surname Italian-language surnames ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to intensive agriculture; deciduous forests in the southeast, now partially cleared, farmed, and settled; and the less populated North Woods, used for mining, forestry, and recreation. Roughly a third of the state is covered in forests, and it is known as the "Land of 10,000 Lakes" for having over 14,000 bodies of fresh water of at least ten acres. More than 60% of Minnesotans live in the Minneapolis–Saint Paul metropolitan area, known as the "Twin Cities", the state's main political, economic, and cultural hub. With a population of about 3.7 million, the Twin Cities is the 16th largest metropolitan area in the U.S. Other minor metropolitan and micropolitan statistical areas in the state include Duluth, Mankato, Moorhead, Rochester, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanographic Instrumentation
Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamics; plate tectonics and the geology of the sea floor; and fluxes of various chemical substances and physical properties within the ocean and across its boundaries. These diverse topics reflect multiple disciplines that oceanographers utilize to glean further knowledge of the world ocean, including astronomy, biology, chemistry, climatology, geography, geology, hydrology, meteorology and physics. Paleoceanography studies the history of the oceans in the geologic past. An oceanographer is a person who studies many matters concerned with oceans, including marine geology, physics, chemistry and biology. History Early history Humans first acquired knowledge of the waves and currents of the seas and oceans in pre-historic times. Observations on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Quality
Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through treatment of the water, can be assessed. The most common standards used to monitor and assess water quality convey the health of ecosystems, safety of human contact, extend of water pollution and condition of drinking water. Water quality has a significant impact on water supply and oftentimes determines supply options. Categories The parameters for water quality are determined by the intended use. Work in the area of water quality tends to be focused on water that is treated for potability, industrial/domestic use, or restoration (of an environment/ecosystem, generally for health of human/aquatic life). Human consumption Contaminants that may be in untreated water include microorganisms such as viruses, protozoa and bacteria; inorg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic State Index
The Trophic State Index (TSI) is a classification system designed to rate water bodies based on the amount of biological productivity they sustain. Although the term "trophic index" is commonly applied to lakes, any surface water body may be indexed. The TSI of a water body is rated on a scale from zero to one hundred. Under the TSI scale, water bodies may be defined as: * oligotrophic (TSI 0–40, having the least amount of biological productivity, "good" water quality); * mesotrophic (TSI 40–60, having a moderate level of biological productivity, "fair" water quality); or * eutrophic to hypereutrophic (TSI 60–100, having the highest amount of biological productivity, "poor" water quality). The quantities of nitrogen, phosphorus, and other biologically useful nutrients are the primary determinants of a water body's TSI. Nutrients such as nitrogen and phosphorus tend to be limiting resources in standing water bodies, so increased concentrations tend to result in increased p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siemens Star
A Siemens star, or spoke target, is a device used to test the resolution of optical instruments, printers, and displays. It consists of a pattern of bright "spokes" on a dark background that radiate from a common center and become wider as they get further from it. In concept, the spokes only meet at the exact center of the star – the spokes, and the gaps between them, become narrower the closer to the center one looks, but they never touch except at the center. When printed or displayed on a device with limited resolution, however, the spokes touch at some distance from the center. The smallest gap visible is limited by the smallest dot of ink the printer can produce, making the Siemens star a useful tool for comparing two printers' resolutions (DPI). Similarly, it can be applied to a camera's optical resolution by taking photographs of a Siemens star printed at high resolution and comparing photographs from different cameras, to see which retained the center detail the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forel-Ule Scale
The Forel-Ule scale is a method to estimate the color of bodies of water. The scale provides a visual estimate of the color of a body of water, and it is used in limnology and oceanography with the aim of measuring the water's transparency and classifying its biological activity, dissolved substances, and suspended sediments. The color scale of 21 different colors can be created using either a set of liquid vials or a set of color lighting filters in a white frame. The classic Forel-Ule Scale uses a set of liquid vials of multiple colors. Together, the liquid vials represent a standardized color palette created by using a set of small transparent glass tubes containing colored water by adding different concentrations of stable inorganic salts. By mixing different chemicals (distilled water, ammonia, copper sulphate, potassium-chromate and cobalt-sulphate) a standard color scale is produced in a set of numbered vials (1-21). The set of vials is then compared with the color of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmissometer
A transmissometer or transmissiometer is an instrument for measuring the extinction coefficient of the atmosphere and sea water, and for the determination of visual range. It operates by sending a narrow, collimated beam of energy (usually a laser) through the propagation medium. A narrow field of view receiver at the designated measurement distance determines how much energy is arriving at the detector, and determines the path transmission and/or extinction coefficient. In a transmissometer the extinction coefficient is determined by measuring direct light transmissivity, and the extinction coefficient is then used to calculate visibility range. Atmospheric extinction is a wavelength dependent phenomenon, but the most common wavelength in use for transmissometers is 550 nm, which is in the middle of the visible waveband, and allows a good approximation of visual range. Transmissometers are also referred to as telephotometers, transmittance meters, or hazemeters. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nephelometer
A nephelometer or aerosol photometer is an instrument for measuring the concentration of suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam (source beam) and a light detector set to one side (often 90°) of the source beam. Particle density is then a function of the light reflected into the detector from the particles. To some extent, how much light reflects for a given density of particles is dependent upon properties of the particles such as their shape, color, and reflectivity. Nephelometers are calibrated to a known particulate, then use environmental factors (k-factors) to compensate lighter or darker colored dusts accordingly. K-factor is determined by the user by running the nephelometer next to an air sampling pump and comparing results. There are a wide variety of research-grade nephelometers on the market as well as open source varieties. Nephelometer uses The main uses of nephelometers rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photometer
A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, photodiode, or photomultiplier. Photometers measure: *Illuminance * Irradiance *Light absorption * Scattering of light * Reflection of light * Fluorescence * Phosphorescence * Luminescence History Before electronic light sensitive elements were developed, photometry was done by estimation by the eye. The relative luminous flux of a source was compared with a standard source. The photometer is placed such that the illuminance from the source being investigated is equal to the standard source, as the human eye can judge equal illuminance. The relative luminous fluxes can then be calculated as the illuminance decreases proportionally to the inverse square of distance. A standard example of such a photometer consists of a piece of paper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wisconsin
Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. The bulk of Wisconsin's population live in areas situated along the shores of Lake Michigan. The largest city, Milwaukee, anchors its largest metropolitan area, followed by Green Bay and Kenosha, the third- and fourth-most-populated Wisconsin cities respectively. The state capital, Madison, is currently the second-most-populated and fastest-growing city in the state. Wisconsin is divided into 72 counties and as of the 2020 census had a population of nearly 5.9 million. Wisconsin's geography is diverse, having been greatly impacted by glaciers during the Ice Age with the exception of the Driftless Area. The Northern Highland and Western Upland along wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sherwood B
Sherwood may refer to: Places Australia *Sherwood, Queensland, a suburb of Brisbane * Sherwood, South Australia, a locality *Shire of Sherwood, a former local government area of Queensland * Electoral district of Sherwood, an electoral district from 1950 to 1992 Canada * Sherwood, Calgary, Alberta, a neighborhood * Sherwood (Edmonton), Alberta, a neighborhood * Sherwood Park, the seat of Strathcona County, Alberta *Sherwood, Ontario, a community in Huron Shores, Ontario *Sherwood, Ontario, a community in Maple, Ontario * Sherwood, Nova Scotia, a community *Sherwood, Prince Edward Island, a neighborhood of Charlottetown *Rural Municipality of Sherwood No. 159, Saskatchewan United Kingdom *Sherwood Forest, north of the city of Nottingham, England; the place where the legendary Robin Hood is said to have lived *Sherwood, Nottingham, a residential area of Nottingham *Sherwood (UK Parliament constituency) United States Lakes * Lake Sherwood (California), a reservoir * Lake Sherwood ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
