Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, spacecraft, guided missiles, motor vehicles, weather formations, terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the object. Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed. Radar was developed secretly for military use by several nations in the period before and during World War II. A key development was the cavity magnetron in the UK, which allowed the creation of small systems with sub-meter resolution; the term RADAR was coined in 1940 by the United States Navy as an acronym for RAdio Detection And Ranging The term radar has since entered English and other languages as a common noun, losing all capitalization.
The modern uses of radar are diverse, including air and terrestrial traffic control, radar astronomy, air-defense systems, antimissile systems, marine radars to locate landmarks and other ships, aircraft anticollision systems, ocean surveillance systems, outer space surveillance and rendezvous systems, meteorological precipitation monitoring and flight control systems, guided missile target locating systems, ground-penetrating radar for geological observations, range-controlled radar for public health surveillance. High tech radar systems are associated with digital signal processing, machine learning and are capable of extracting useful information from high noise levels. Radar is a key technology that the self-driving systems are designed to use, along with sonar and other sensors. Other systems similar to radar make use of other parts of the electromagnetic spectrum. One example is "lidar". With the emergence of driverless vehicles, Radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents.
As early as 1886, German physicist Heinrich Hertz showed that radio waves could be reflected from solid objects. In 1895, Alexander Popov, a physics instructor at the Imperial Russian Navy school in Kronstadt, developed an apparatus using a coherer tube for detecting distant lightning strikes; the next year, he added a spark-gap transmitter. In 1897, while testing this equipment for communicating between two ships in the Baltic Sea, he took note of an interference beat caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation; the German inventor Christian Hülsmeyer was the first to use radio waves to detect "the presence of distant metallic objects". In 1904, he demonstrated the feasibility of detecting a ship in dense fog, but not its distance from the transmitter, he obtained a patent for his detection device in April 1904 and a patent for a related amendment for estimating the distance to the ship.
He got a British patent on September 23, 1904 for a full radar system, that he called a telemobiloscope. It operated on a 50 cm wavelength and the pulsed radar signal was created via a spark-gap, his system used the classic antenna setup of horn antenna with parabolic reflector and was presented to German military officials in practical tests in Cologne and Rotterdam harbour but was rejected. In 1915, Robert Watson-Watt used radio technology to provide advance warning to airmen and during the 1920s went on to lead the U. K. research establishment to make many advances using radio techniques, including the probing of the ionosphere and the detection of lightning at long distances. Through his lightning experiments, Watson-Watt became an expert on the use of radio direction finding before turning his inquiry to shortwave transmission. Requiring a suitable receiver for such studies, he told the "new boy" Arnold Frederic Wilkins to conduct an extensive review of available shortwave units. Wilkins would select a General Post Office model after noting its manual's description of a "fading" effect when aircraft flew overhead.
Across the Atlantic in 1922, after placing a transmitter and receiver on opposite sides of the Potomac River, U. S. Navy researchers A. Hoyt Taylor and Leo C. Young discovered that ships passing through the beam path caused the received signal to fade in and out. Taylor submitted a report, suggesting that this phenomenon might be used to detect the presence of ships in low visibility, but the Navy did not continue the work. Eight years Lawrence A. Hyland at the Naval Research Laboratory observed similar fading effects from passing aircraft. Before the Second World War, researchers in the United Kingdom, Germany, Japan, the Netherlands, the Soviet Union, the United States, independently and in great secrecy, developed technologies that led to the modern version of radar. Australia, New Zealand, South Africa followed prewar Great Britain's radar development, Hungary generated its radar technology during the war. In France in 1934, following systematic studies on the split-anode magnetron, the research branch of the Compagnie Générale de Télégraphie Sans Fil headed by Maurice Ponte with Henri Gutton, Sylvain Berline and M. Hugon, began developing an obstacle-locatin
Arctic grayling is a species of freshwater fish in the salmon family Salmonidae. T. arcticus is widespread throughout the Arctic and Pacific drainages in Canada and Siberia, as well as the upper Missouri River drainage in Montana. In the U. S. state of Arizona, an introduced population is found in the Lee Valley and other lakes in the White Mountains. They were stocked at Toppings Lake by the Teton Range and in various lakes in the high Uinta Mountains in Utah; the scientific name of the Arctic grayling is Thymallus arcticus. It was named in 1776 by German zoologist Peter Simon Pallas from specimens collected in Russia; the name of the genus Thymallus first given to grayling described in the 1758 edition of Systema Naturae by Swedish zoologist Carl Linnaeus originates from the faint smell of the herb thyme, which emanates from the flesh. Arctic grayling grow to a maximum recorded weight of 3.8 kg. Of typical thymalline appearance, the Arctic grayling is distinguished from the similar grayling by the absence of dorsal and anal spines and by the presence of a larger number of soft rays in these fins.
There is a dark midlateral band between the pectoral and pelvic fins, the flanks may possess a pink iridescence. T. a. arcticus has been recorded as reaching an age of 18 years. Arctic grayling are widespread in Arctic Ocean drainages from Hudson Bay, Canada to Alaska and in Arctic and Pacific drainages to central Alberta and British Columbia in Canada, they do not occur in the Fraser and Columbia river basins. There are remnant native populations of fluvial Arctic grayling in the upper Missouri River drainage in the Big Hole River and Red Rock basin. Fluvial Arctic grayling have been reestablished in the upper Ruby River, a tributary of the Beaverhead River; the native range extended south into the Great Lakes basin in Michigan. They occur in the Arctic Ocean basin in Siberia from the Ob to Yenisei drainages and in European Russia in some tributaries of Pechora river. Lake dwelling forms of Arctic grayling have been introduced in suitable lake habitats throughout the Rocky Mountains including lakes in the Teton Range in Wyoming and the high Uinta Mountains in Utah), Cascade Mountains and Sierra Nevada Mountains as far south as Arizona.
Several life history forms of Arctic grayling occur: fluvial populations that live and spawn in rivers. The Arctic grayling occurs in cold waters of mid-sized to large rivers and lakes, returning to rocky streams to breed; the various subspecies are omnivorous. Crustaceans and insect larvae, fish eggs form the most important food items. Larger specimens of T. arcticus become piscivorous and the immature fish feed on zooplankton and insect larvae. Spawning takes place in the spring. Adult fish seek shallow areas of rivers with fine, sand substrate and moderate current. Males are court females by flashing their colourful dorsal fins; the fish are nonguarders: the eggs are left to mix with the substrate. Although the Arctic grayling does not excavate a nest, the energetic courtship and mating tends to kick up fine material which covers the zygotes; the zygote is small and the embryo will hatch after two to three weeks. The newly hatched embryo remains in the substrate, they emerge at a length of around 12 to 18 mm.
The juveniles grow during their first two years of life. Arctic grayling are considered a secure species throughout their range. Although some populations at the southern extant of its native range have been extirpated, it remains widespread elsewhere and is not listed on the IUCN Red List of threatened species; the fluvial population in the upper Missouri river basin once merited a high priority for listing under the Endangered Species Act by the US Fish & Wildlife Service. This unique southernmost population is now extirpated from all areas of the basin with the exception of the Big Hole River watershed. In preparation for an ESA listing, the US FWS began implementing a "Candidate Conservation Agreement with Assurances"; this agreement protects cooperating landowners from being prosecuted under the ESA "takings" clause so long as they fulfill specific obligations, spelled out in a contractual arrangement and intended to restore the dwindling population. In 2014 the FWS determined not to list the grayling under ESA, due to the effectiveness of the CCAA.
The Arctic grayling is economically important. Citations SourcesFroese and Pauly, eds.. "Thymallus arcticus" in FishBase. February 2012 version. FWS. U. S. Fish and Wildlife Service Species Assessment and Listing Priority Assignment Form for fluvial Arctic grayling called Montana Arctic grayling. November 30, 2004. EcoRover blog about Big Hole River grayling Pat Munday's rating of Big Hole Watershed Committee effectiveness in Big Hole River grayling restoration Length and age at maturity of Arctic grayling in the Snake River during 2003 / by Alfred L. DeCicco and Andrew D. Gryska. Hosted by Alaska State Publications Program. Summer abundance of Arctic grayling in the Chena Riv
A tarn is a mountain lake, pond or pool, formed in a cirque excavated by a glacier. A moraine may form a natural dam below a tarn; the word is derived from the Old Norse word tjörn meaning pond. Its more specific use as a mountain lake emerges as it is the used term for all ponds in the upland areas of Northern England. Here, it retains a broader use, referring to any small lake or pond, regardless of its location and origin. In Scandinavian languages, a tjern or tjärn, tärn or tjørn is a small natural lake in a forest or with vegetation surrounding it or growing into the tarn. Pond Proglacial lake
Dolly Varden trout
For other species or known as "Dolly Varden trout", see bull trout and Arctic char. The Dolly Varden trout is a species of salmonid native to cold-water tributaries of the Pacific Ocean in Asia and North America, it is in the genus Salvelinus of true chars, which includes 51 recognized species, the most prominent being the brook and bull trout, as well as Arctic char. Although many populations are semi-anadromous and lacustrine populations occur throughout its range, it is considered by taxonomists as part of the Salvelinus alpinus or Arctic char complex, as many populations of bull trout, Dolly Varden trout and Arctic char overlap. The scientific name of the Dolly Varden is Salvelinus malma; the species was named by German naturalist and taxonomist Johann Julius Walbaum in 1792 based on type specimens from the Kamchatka Peninsula in Siberia. The name malma was based on the local Russian colloquial name for the fish; the Dolly Varden trout is considered part of the S. alpinus or Arctic char complex.
For most of the 19th and 20th centuries, the Dolly Varden trout and the bull trout were considered the same species. Additionally, the Arctic char along with the bull trout have ranges that overlap and are remarkably similar in appearance, thus complicating identification. In 1978, inland forms of the Dolly Varden trout were reclassified as Salvelinus confluentus, retaining the common name bull trout, it appears that the first recorded use of the Dolly Varden name for fish referred to S. confluentus, now known as the bull trout. This was due to overlapping ranges and similar appearances among members of the two species. In North America, two subspecies of Dolly Varden are distinguished, the Northern Dolly Varden of the Arctic drainages and the Southern Dolly Varden of the Pacific drainages; these can be distinguished as separate mitochondrial lineages also. The status of the Beringian drainage populations remains unclear. Northern populations on the Russian side of the Pacific down to Kamchatka are considered S. m. malma, the southerly populations make another lineage and subspecies, the Asian Dolly Varden S. m. krascheninnikova.
The landlocked Miyabe Char from Lake Shikaribetsu on Hokkaido in Japan is included in the Dolly Varden species. S. m. malma S. m. lordi S. m. krascheninnikova = Salvelinus curilus S. m. miyabei The first recorded use of the name "Dolly Varden" was applied to members of S. confluentus caught in the McCloud River in northern California in the early 1870s. In his book, Inland Fishes of California, Peter Moyle recounts a letter sent to him on March 24, 1974, from Valerie Masson Gomez: My grandmother's family operated a summer resort at Upper Soda Springs on the Sacramento River just north of the present town of Dunsmuir, California, she lived there all her life and related to us in her years her story about the naming of the Dolly Varden trout. She said that some fishermen were standing on the lawn at Upper Soda Springs looking at a catch of the large trout from the McCloud River that were called'calico trout' because of their spotted, colorful markings, they were saying. My grandmother a young girl of 15 or 16, had been reading Charles Dickens' Barnaby Rudge in which there appears a character named Dolly Varden.
My grandmother had just gotten a new dress in that style and the red-spotted trout reminded her of her printed dress. She suggested to the men looking down at the trout,'Why not call them "Dolly Varden"?' They thought it a appropriate name and the guests that summer returned to their homes calling the trout by this new name. David Starr Jordan, while at Stanford University, included an account of this naming of the Dolly Varden Trout in one of his books. In 1874, Livingston Stone, a naturalist working for the U. S. government, wrote of this fish: Also called at Soda Springs the'Varden' trout.... The handsomest trout, and, on the whole, having the most perfect form of all the trout we saw on the McCloud; the only fish that had colored spots. This one was profusely spotted over most of the body with reddish golden spots.... The local name at Soda Springs is the Dolly Varden. Although the name "Dolly Varden" was given to the bull trout of the McCloud River, bull trout and Dolly Varden trout were considered the same species until 1978.
Thus the common name "Dolly Varden" gained acceptance for S. malma for over 100 years. Additionally, the Arctic char and Russian subspecies have been referred to as Dolly Varden, it is known as belyi golets in Russian. The back and sides are muddy gray, shading to white on the belly; the body has scattered pale pinkish-yellow spots. There are no black spots or wavy lines on fins. Small red spots are present on the lower sides; these are indistinct. The fins are unmarked except for a few light spots on the base of the caudal fin rays. S. malma is similar in appearance to the bull trout and Arctic char, so much so that they are sometimes referred to as "native char" without a distinction. The Dolly Varden trout is found in coastal waters of the North Pacific from Puget Sound north along the British C
The Kigluaik Mountains are a 42-mile mountain chain running east to west on western Alaska's Seward Peninsula. Its highest point is the summit of Mount Osborn, at 4,714 feet above sea level; this remote range is home to numerous isolated mountain lakes which have been shown to contain unique subspecies of Arctic char. Located in the Nome Census Area, Kigluaik Mountains are noted as the location of Grand Union Glacier, the only remaining active glacier in western Alaska
Norton Sound is an inlet of the Bering Sea on the western coast of the U. S. state of Alaska, south of the Seward Peninsula. It is 200 km wide; the Yukon River delta forms a portion of the south shore and water from the Yukon influences this body of water. It is ice-free from June to October. Norton Sound was explored by Captain James Cook in September 1778, he named the body of water after Sir Fletcher Norton Speaker of the British House of Commons. The Norton Sound area has been home to Yup ` Inupiat for many centuries, it is the boundary between the two peoples. The town of Nome is along the northern edge of Norton Sound; the villages of Elim, Stebbins, White Mountain, Shaktoolik, St. Michael, Unalakleet are on the shores or waterways flowing into Norton Sound; the Iditarod Trail Sled Dog Race runs through coastal villages between Nome. The seaplane tender USS Norton Sound was named after the inlet. Norton Sound Encyclopædia Britannica U. S. Geological Survey Geographic Names Information System: Norton Sound
Northwest Arctic Borough, Alaska
Northwest Arctic Borough is a borough located in the U. S. state of Alaska. As of the 2010 census, the population was 7,523; the borough seat is Kotzebue. The borough was formed on June 2, 1986. According to the U. S. Census Bureau, the borough has a total area of 40,749 square miles, of which 35,573 square miles is land and 5,176 square miles is water. By land area, it is larger in total area than the state of Indiana, its coastline is limited by the Chukchi Sea. The Kotzebue Sound, a significant wildlife area, is a prominent water body within the Northwest Arctic Borough; the largest polar bear sighted in history, a male weighing 2209 pounds, was sighted at Kotzebue sound. North Slope Borough, Alaska - north Yukon-Koyukuk Census Area, Alaska - east Nome Census Area, Alaska - south Alaska Maritime National Wildlife Refuge Chamisso Wilderness Bering Land Bridge National Preserve Cape Krusenstern National Monument Gates of the Arctic National Park and Preserve Gates of the Arctic Wilderness Kobuk Valley National Park Kobuk Valley Wilderness Koyukuk National Wildlife Refuge Noatak National Preserve Noatak Wilderness Selawik National Wildlife Refuge Selawik Wilderness At the 2000 census, there were 7,208 people, 1,780 households and 1,404 families residing in the borough.
The population density was 0.18 per square mile. There were 2,540 housing units at an average density of 0 per square mile; the racial makeup of the borough was 12.32% White, 0.21% Black or African American, 82.46% Native American, 0.89% Asian, 0.06% Pacific Islander, 0.36% from other races, 3.70% from two or more races. 0.79% of the population were Hispanic or Latino of any race. 40.00 % "Eskimo" at home. There were 1,780 households of which 55.20% had children under the age of 18 living with them, 47.90% were married couples living together, 19.70% had a female householder with no husband present, 21.10% were non-families. 16.60% of all households were made up of individuals and 2.10% had someone living alone, 65 years of age or older. The average household size was 3.87 and the average family size was 4.36. Age distribution was 41.50% under the age of 18, 10.00% from 18 to 24, 28.10% from 25 to 44, 15.50% from 45 to 64, 5.00% who were 65 years of age or older. The median age was 24 years. For every 100 females, there were 114.50 males.
For every 100 females age 18 and over, there were 120.70 males. Noatak Red Dog Mine List of airports in the Northwest Arctic Borough Official website Borough map: Alaska Department of Labor Summaries of Division of Subsistence research projects in northwest Alaska / Division of Subsistence, Alaska Department of Fish and Game. Hosted by the Alaska State Publications Program. Subsistence wildlife harvests in five northwest Alaska communities, 2001-2003: results of a household survey / by Kawerak, Inc. Maniilaq Association, the Alaska Department of Fish and Game. Hosted by Alaska State Publications Program