1.
Death Valley National Park
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Death Valley National Park is a national park in the United States. Straddling the border of California and Nevada, located east of the Sierra Nevada, the park protects the northwest corner of the Mojave Desert and contains a diverse desert environment of salt-flats, sand dunes, badlands, valleys, canyons, and mountains. It is the largest national park in the lower 48 states and has declared an International Biosphere Reserve. Approximately 91% of the park is a wilderness area. It is the hottest, driest and lowest of the parks in the United States. The second-lowest point in the Western Hemisphere is in Badwater Basin, the park is home to many species of plants and animals that have adapted to this harsh desert environment. Some examples include creosote bush, bighorn sheep, coyote, and the Death Valley pupfish, several short-lived boom towns sprang up during the late 19th and early 20th centuries to mine gold and silver. The only long-term profitable ore to be mined was borax, which was transported out of the valley with twenty-mule teams, the valley later became the subject of books, radio programs, television series, and movies. Tourism blossomed in the 1920s, when resorts were built around Stovepipe Wells, Death Valley National Monument was declared in 1933 and the park was substantially expanded and became a national park in 1994. The natural environment of the area has been shaped largely by its geology, the valley itself is actually a graben. The oldest rocks are metamorphosed and at least 1.7 billion years old. Ancient, warm, shallow seas deposited marine sediments until rifting opened the Pacific Ocean, additional sedimentation occurred until a subduction zone formed off the coast. This uplifted the region out of the sea and created a line of volcanoes, later the crust started to pull apart, creating the current Basin and Range landform. Valleys filled with sediment and, during the wet times of glacial periods, with lakes, in 2013, Death Valley National Park was designated as a dark sky park by the International Dark-Sky Association. There are two valleys in the park, Death Valley and Panamint Valley. Both of these valleys were formed within the last few million years, the result of this shearing action is additional extension in the central part of Death Valley which causes a slight widening and more subsidence there. Uplift of surrounding mountain ranges and subsidence of the floor are both occurring. The uplift on the Black Mountains is so fast that the fans there are small
2.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
3.
Eastern California
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Eastern California is a region defined as either the strip to the east of the crest of the Sierra Nevada or as the easternmost counties of California in the United States. Most of Eastern California does not fit the stereotypes of California and is related in culture to southeastern Oregon, northwestern Nevada. Northeastern California is very populated and tends to be politically conservative. Historically, Northeastern California has had ties to Nevada, with the exact boundary between the two states in some dispute. Residents of portions of near Susanville, California, tried to break away from California in 1856, first by declaring themselves part of the Nataqua Territory, the two states further squabbled over ownership of Susanville in 1863. The town of Aurora, Nevada, was temporarily the county seat of both Mono County, California, and Esmeralda County, Nevada, finally, the line between the two states was settled by a survey in 1872. Indeed, the hottest and lowest area in North America lies in Eastern California, geologically, Eastern California is mostly part of the Basin and Range Province, marked by crustal extension, with horsts and grabens. Volcanism is also evident in this region
4.
Mojave Desert
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The Mojave Desert is an arid rain-shadow desert and the driest desert in North America. It is located in the southwestern United States, primarily within southeastern California and southern Nevada, very small areas also extend into Utah and Arizona. The central part of the desert is sparsely populated, while its peripheries support large communities such as Las Vegas, Lancaster, Palmdale, Victorville, the Mojave Desert is bordered by the Great Basin Desert to its north and the Sonoran Desert to its south and east. Topographical boundaries include the Tehachapi Mountains to the west, and the San Gabriel Mountains, the mountain boundaries are distinct because they are outlined by the two largest faults in California – the San Andreas and Garlock faults. The Mojave Desert displays typical basin and range topography and it occupies less than 50,000 sq mi, making it the smallest of the North American deserts. The Mojave Desert is often referred to as the desert, in contrast to the low desert. However, the Mojave Desert is generally lower than the Great Basin Desert to the north, the spelling Mojave originates from the Spanish language while the spelling Mohave comes from modern English. The Mojave Desert receives less than 13 in of rain a year and is generally between 2,000 and 5,000 feet in elevation, zion National Park in Utah lies at the junction of the Mojave, the Great Basin Desert, and the Colorado Plateau. Despite its aridity, the Mojave has long been a center of production, fed by irrigation coming from groundwater. The Mojave is a desert of temperature extremes and two distinct seasons, winter months bring comfortable daytime temperatures, which dip precipitously to around 20 °F on valley floors, and below 0 °F at higher elevations. Storms moving from the Pacific Northwest can bring rain and in places even snow. More often, the shadow created by the Sierra Nevada as well as mountain ranges within the desert such as the Spring Mountains, bring only clouds. By early June, it is rare for another Pacific storm to have a significant impact on the regions weather, summer weather is dominated by heat. Temperatures on valley floors can soar above 120 °F and above 130 °F at the lowest elevations, low humidity, high temperatures, and low pressure, draw in moisture from the Gulf of Mexico creating thunderstorms across the desert southwest known as the North American monsoon. Autumn is generally pleasant, with one to two Pacific storm systems creating regional rain events, october is one of the driest and sunniest months in the Mojave, and temperatures usually remain between 70 °F and 90 °F on the valley floors. After temperature, wind is the most significant weather phenomenon in the Mojave, during the June Gloom, cooler air can be pushed out into the desert from Southern California. In Santa Ana wind events, hot air from the desert blows out into the Los Angeles basin, wind farms in these areas generate power from these winds. The other major factor in the region is elevation
5.
Great Basin Desert
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The Great Basin Desert is part of the Great Basin between the Sierra Nevada and the Wasatch Range. It is a desert with hot, dry summers and snowy winters. The desert spans a large part of the state of Nevada, and extends into western Utah, eastern California, the desert is one of the four biologically defined deserts in North America, in addition to the Mojave, Sonoran, and Chihuahuan Deserts. Basin and range topography characterizes the desert, wide valleys bordered by mountain ranges generally oriented north-south. There are more than 33 peaks within the desert with summits higher than 9,800 feet, the biological communities of the Great Basin Desert vary according to altitude, from low salty dry lakes, up through rolling sagebrush valleys, to pinyon-juniper forests. According to Grayson, more than 600 species of live in the floristic Great Basin. Sixty-three of these species have been identified as species of concern due to contracting natural habitats. The ecology of the desert varies across geography, also, different locations in the desert have different amounts of precipitation, depending on the strength of these rain shadows. The environment is influenced by Pleistocene lakes that dried after the last ice age, Lake Lahontan, each of these lakes left different amounts of salinity and alkalinity. The Great Basin Desert is defined by its animals and plants, scientists have different definitions of the Great Basin Desert, which are often defined by negatives. J. Robert Macey defines the Great Basin scrub desert as lacking creosote bush, the Great Basin Desert includes several arid basins lacking Larrea tridentata such as the Chalfant, Hammil, Benton, and Queen valleys, as well as all but the southeast portion of the Owens Valley. Conversely, the Panamint, Saline, and Eureka valleys have creosote bush, the study and definition of ecoregions can also indicate the boundaries of the Great Basin Desert. In 1987, J. M. Omernik defined a desert ecoregion between the Sierra Nevada and Wasatch Range, naming it the Northern Basin and Range ecoregion. In 1999, the U. S. EPA renamed the Northern Basin and Range to Central Basin and Range and he states that the Great Basin Desert is encompassed within that area. This article describes the ecology of the region, including the high-elevation areas. See Great Basin montane forests for more details on the high-elevation ecoregion. This is the climate of the high desert, the Great Basin desert climate begins with the Sierra Nevada in eastern California. Rising 14,000 feet above sea level, this mountain range casts a rain shadow over the desert
6.
Middle East
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The Middle East is a transcontinental region centered on Western Asia and Egypt. The corresponding adjective is Middle-Eastern and the noun is Middle-Easterner. The term has come into usage as a replacement of the term Near East beginning in the early 20th century. Arabs, Turks, Persians, Kurds, and Azeris constitute the largest ethnic groups in the region by population. Indigenous minorities of the Middle East include Jews, Assyrians and other Arameans, Baloch, Berbers, Copts, Druze, Lurs, Mandaeans, Samaritans, Shabaks, Tats, in the Middle East, there is also a Romani community. European ethnic groups form a diaspora in the region include Albanians, Bosniaks, Circassians, Crimean Tatars, Franco-Levantines. Among other migrant populations are Bengalis as well as other Indians, Chinese, Filipinos, Indonesians, Pakistanis, the history of the Middle East dates back to ancient times, with the importance of the region being recognized for millennia. Most of the countries border the Persian Gulf have vast reserves of crude oil. The term Middle East may have originated in the 1850s in the British India Office, however, it became more widely known when American naval strategist Alfred Thayer Mahan used the term in 1902 to designate the area between Arabia and India. During this time the British and Russian Empires were vying for influence in Central Asia, Mahan realized not only the strategic importance of the region, but also of its center, the Persian Gulf. Mahan first used the term in his article The Persian Gulf and International Relations, published in September 1902 in the National Review, a British journal. The Middle East, if I may adopt a term which I have not seen, will some day need its Malta, as well as its Gibraltar, it does not follow that either will be in the Persian Gulf. The British Navy should have the facility to concentrate in force if occasion arise, about Aden, India, mahans article was reprinted in The Times and followed in October by a 20-article series entitled The Middle Eastern Question, written by Sir Ignatius Valentine Chirol. During this series, Sir Ignatius expanded the definition of Middle East to include regions of Asia which extend to the borders of India or command the approaches to India. After the series ended in 1903, The Times removed quotation marks from subsequent uses of the term, in the late 1930s, the British established the Middle East Command, which was based in Cairo, for its military forces in the region. After that time, the term Middle East gained broader usage in Europe, the description Middle has also led to some confusion over changing definitions. Before the First World War, Near East was used in English to refer to the Balkans and the Ottoman Empire, while Middle East referred to Iran, the Caucasus, Afghanistan, Central Asia, and Turkestan. The first official use of the term Middle East by the United States government was in the 1957 Eisenhower Doctrine, the Associated Press Stylebook says that Near East formerly referred to the farther west countries while Middle East referred to the eastern ones, but that now they are synonymous
7.
Badwater Basin
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Badwater Basin is an endorheic basin in Death Valley National Park, Death Valley, Inyo County, California, noted as the lowest point in North America, with an elevation of 282 ft below sea level. Mount Whitney, the highest point in the contiguous 48 United States, is only 84.6 miles to the north west. The site itself consists of a small spring-fed pool of bad water next to the road in a sink, the pool does have animal and plant life, including pickleweed, aquatic insects, and the Badwater snail. Adjacent to the pool, where water is not always present at the surface, repeated freeze–thaw, the pool is not the lowest point of the basin, the lowest point is several miles to the west and varies in position, depending on rainfall and evaporation patterns. The salt flats are hazardous to traverse, and so the sign marking the low point is at the pool instead, the basin was considered the lowest elevation in the Western Hemisphere until the discovery of Laguna del Carbón in Argentina at −344 ft. At Badwater Basin, significant rainstorms flood the valley bottom periodically, newly formed lakes do not last long though, because the 1.9 in of average rainfall is overwhelmed by a 150 in annual evaporation rate. This is the greatest evaporation potential in the United States, meaning that a 12 ft lake could dry up in a single year, when the basin is flooded, some of the salt is dissolved, it is redeposited as clean crystals when the water evaporates. A popular site for tourists is the sign marking sea level on the cliff above the Badwater Basin, numerous evaporation cycles and a lack of outflow caused an increasing hypersalinity, typical for endorheic bodies of water. Over time, this hypersalinization, combined with sporadic rainfall and occasional aquifer intrusion, has resulted in periods of briny soup, or salty pools, on the lowest parts of Death Valleys floor. Salts began to crystallize, coating the surface with the thick crust, ranging from 3 to 60 in, Death Valley pupfish List of elevation extremes by country List of elevation extremes by region John McKinney, Californias Desert Parks, A Day Hikers Guide. Wilderness Press 2006, ISBN 0-89997-389-2, S. 54–55 Don J. Easterbrook, geological Society of America 2003, ISBN 94-592-0504-6, S. 63–64 Badwater Basin in the Encyclopædia Britannica
8.
Mount Whitney
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Mount Whitney is the highest summit in the contiguous United States and the Sierra Nevada, with an elevation of 14,505 feet. The west slope of the mountain is in Sequoia National Park, the east slope is in the Inyo National Forest in Inyo County. The summit of Whitney is on the Sierra Crest and the Great Basin Divide and it lies near many of the highest peaks of the Sierra Nevada. The peak rises dramatically above the Owens Valley, sitting 10,778 feet or just over two miles above the town of Lone Pine 15 miles to the east, in the Owens Valley. It rises more gradually on the west side, lying only about 3,000 feet above the John Muir Trail at Guitar Lake, the mountain is partially dome-shaped, with its famously jagged ridges extending to the sides. Mount Whitney is above the line and has an alpine climate. Very few plants grow near the summit, one example is the Skypilot, the only animals are transient, such as the butterfly Parnassius phoebus and the gray-crowned rosy finch. The mountain is the highest point on the Great Basin Divide, waterways on the west side of the peak flow into Whitney Creek, which flows into the Kern River. The Kern River terminates in the Tulare Basin, during very wet years, water overflows from the Tulare Basin into the San Joaquin River which flows to the Pacific Ocean. From the east, water from Mount Whitney flows to Lone Pine Creek, which joins the Owens River, which in turn terminates at Owens Lake, the estimated elevation of the summit of Mount Whitney has changed over the years. The technology of elevation measurement has become refined and, more importantly. The peak was commonly said to be at 14,494 ft, an older plaque on the summit reads elevation 14,496.811 feet but this was estimated using the older vertical datum from 1929. Since then the shape of the Earth has been estimated more accurately, using a new vertical datum established in 1988 the benchmark is now estimated to be at 14,505 ft. The rise is caused by a fault system that runs along the eastern base of the Sierra. Thus, the granite that forms Mount Whitney is the same as the granite that forms the Alabama Hills, the raising of Whitney is due to the same geological forces that cause the Basin and Range Province, the crust of much of the intermontane west is slowly being stretched. The granite that forms Mount Whitney is part of the Sierra Nevada batholith, in Cretaceous time, masses of molten rock that originated from subduction rose underneath what is now Whitney and solidified underground to form large expanses of granite. In July 1864, the members of the California Geological Survey named the peak after Josiah Whitney, during the same expedition, geologist Clarence King attempted to climb Whitney from its west side, but stopped just short. In 1871, King returned to climb what he believed to be Whitney, upon learning of his mistake in 1873, King finally completed his own first ascent of Whitney, but did so a month too late to claim the first recorded ascent
9.
Contiguous United States
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The contiguous United States consists of the 48 adjoining U. S. states plus Washington, D. C. on the continent of North America. S. The greatest distance entirely within the 48 contiguous states is 2,802 miles, the greatest north-south line is 1,650 miles. Together, the 48 contiguous states and Washington, D. C. occupy an area of 3,119,884.69 square miles. Of this area,2,959,064.44 square miles is land, composing 83. 65% of U. S. land area, officially,160,820.25 square miles is water area, composing 62. 66% of the nations total water area. The contiguous United States would be placed 5th in the list of states and dependencies by area. The 2010 census population of area was 306,675,006, comprising 99. 33% of the nations population. While conterminous U. S. has the meaning of contiguous U. S. other terms commonly used to describe the 48 contiguous states have a greater degree of ambiguity. The term was in use prior to the admission of Alaska and Hawaii as states of the United States, the District of Columbia is not always specifically mentioned as being part of CONUS. OCONUS is derived from CONUS with O for outside added, thus referring to Outside of Continental United States, the term Lower 48 is also used to refer to the conterminous United States. The National Geographic style guide recommends the use of contiguous or conterminous United States instead of lower 48 when the 48 states are meant, both Alaskans and Hawaiians have unique labels for the contiguous United States because of their own locations relative to them. Alaska became the 49th state of the United States on January 3,1959, Alaska is on the northwest end of the North American continent, but separated from the rest of the United States Pacific coast by the Canadian province of British Columbia. In Alaska, given the ambiguity surrounding the usage of continental, several other terms have been used over the years. Hawaii became the 50th state of the United States on August 21,1959 and it is the southernmost and so far, the latest state to join the Union. Not part of any continent, Hawaii is located in the Pacific Ocean, about 2,200 miles from North America, in Hawaii and overseas American territories, for instance, the terms the Mainland or U. S. Mainland are often used to refer to the continental United States, apart from off-shore US islands, a few continental portions of the contiguous US are accessible by road only by traveling through Canada. Point Roberts, Washington, Elm Point, Minnesota, and the Northwest Angle in Minnesota are three such places, alburgh, Vermont, is not directly connected by land, but is accessible by road via bridges from within Vermont and from from New York. The 48 contiguous United States are, Washington, D. C. is distinct from the state of Washington, extreme points of the United States Mainland Definition of continental Definition of contiguous Definition of coterminous and conterminous
10.
Furnace Creek, California
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Furnace Creek is a census-designated place in Inyo County, California. The population was 24 at the 2010 census, down from 31 at the 2000 census, the elevation of the village is 190 feet below sea level. The visitor center, museum, and headquarters of the Death Valley National Park are located at Furnace Creek, the village is surrounded by a number of Park Service public campgrounds. Two of the Parks major tourist facilities, the Furnace Creek Inn, the Furnace Creek Golf Course attached to the Ranch claims to be the lowest in the world, at 214 feet below sea level. There are also a restaurant, cafe, store, and gas station in Furnace Creek village, the Furnace Creek Airport is located about 0.75 miles west of the park headquarters. According to the United States Census Bureau, the CDP has an area of 31.5 square miles. Springs in the Amargosa Range created an oasis at Furnace Creek. From 1911 through 2006, Furnace Creek had a high temperature of 91.4 °F. During that time period, the hottest month was July with a daily high temperature of 116.5 °F. Furnace Creek has the distinction of holding the record for the highest recorded temperature in the world, some meteorologists dispute the accuracy of the 1913 temperature measurement. In addition, a temperature of 201 °F was recorded in Furnace Creek on July 15,1972. The Timbisha Native Americans inhabited what is now known as the Furnace Creek oasis for centuries, Greenland Ranch was established by the William Tell Coleman Borax Company in 1883. It was named after the green Alfalfa fields planted at the location, a Weather Station was established at the ranch in 1891. Greenland Ranch was renamed Furnace Creek Ranch in 1933, the Timbisha tribe currently live at their Death Valley Indian Community reservation here. The Timbisha people provided many of the artisans and builders to construct the original Fred Harvey Company resort buildings, the Indian Village and they were one of the first tribes to secure tribal status through the Bureau of Indian Affairs Federal Acknowledgment Process. Furnace Creek was formerly the center of Death Valley mining and operations for the Pacific Coast Borax Company, on the afternoon of July 10,1913, a temperature of 134 °F was recorded at Greenland Ranch. This temperature stands as the highest ambient air temperature recorded at the surface of the Earth. The 2010 United States Census reported that Furnace Creek had a population of 24, the population density was 0.8 people per square mile
11.
Great Basin
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The Great Basin is the largest area of contiguous endorheic watersheds in North America. The region spans several physiographic divisions, biomes/ecoregions, and deserts, the term Great Basin is applied to hydrographic, biological, floristic, physiographic, topographic, and ethnographic geographic areas. The name was coined by John C. Frémont, who, based on information gleaned from Joseph R. Walker as well as his own travels, the hydrographic definition is the most commonly used, and is the only one with a definitive border. The other definitions yield not only different geographical boundaries of Great Basin regions, the Great Basin physiographic section is a geographic division of the Basin and Range Province defined by Nevin Fenneman in 1931. The United States Geological Survey adapted Fennemans scheme in their Physiographic division of the United States, the section is somewhat larger than the hydrographic definition. The culture area covers approximately 400,000 sq mi, or just less than twice the area of the hydrographic Great Basin, the hydrographic Great Basin is a 209,162 square miles area that drains internally. All precipitation in the region evaporates, sinks underground or flows into lakes, as observed by Frémont, creeks, streams, or rivers find no outlet to either the Gulf of Mexico or the Pacific Ocean. The region is bounded by the Wasatch Mountains to the east, the Sierra Nevada and Cascade Ranges to the west, the south rim is less distinct. The Great Basin includes most of Nevada, half of Utah, substantial portions of Oregon and California and small areas of Idaho, Wyoming, the term Great Basin is slightly misleading, the region is actually made up of many small basins. The Great Salt Lake, Pyramid Lake, and the Humboldt Sink are a few of the drains in the Great Basin, the Salton Sink is another closed basin within the Great Basin. The Great Basin Divide separates the Great Basin from the watersheds draining to the Pacific Ocean, the southernmost portion of the Great Basin is the watershed area of the Laguna Salada. The Great Basins longest and largest river is the Bear River of 350 mi, Lake Tahoe, North Americas largest alpine lake, is part of the Great Basins central Lahontan subregion. The hydrographic Great Basin contains multiple deserts and ecoregions, each with its own set of flora. The ecological boundaries and divisions in the Great Basin are unclear, the Great Basin overlaps four different deserts, portions of the hot Mojave and Colorado Deserts to the south, and the cold Great Basin and Oregon High Deserts in the north. The deserts can be distinguished by their plants, the Joshua tree and creosote bush occur in the hot deserts, the cold deserts are generally higher than the hot, and have their precipitation spread throughout the year. The climate and flora of the Great Basin is strongly dependent on elevation, as the elevation increases, because of this, forests occur at higher elevations. Utah juniper/single-leaf pinyon and mountain mahogany form open pinyon-juniper woodland on the slopes of most ranges, stands of limber pine and Great Basin bristlecone pine can be found in some of the higher ranges
12.
Sierra Nevada (U.S.)
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The Sierra Nevada is a mountain range in the Western United States, between the Central Valley of California and the Basin and Range Province. The vast majority of the lies in the state of California. The Sierra runs 400 miles north-to-south, and is approximately 70 miles across east-to-west, the Sierra is home to three national parks, twenty wilderness areas, and two national monuments. These areas include Yosemite, Sequoia, and Kings Canyon National Parks, the character of the range is shaped by its geology and ecology. More than one hundred years ago during the Nevadan orogeny. The range started to uplift four M. A. ago, the uplift caused a wide range of elevations and climates in the Sierra Nevada, which are reflected by the presence of five life zones. Uplift continues due to faulting caused by forces, creating spectacular fault block escarpments along the eastern edge of the southern Sierra. The Sierra Nevada has a significant history, the California Gold Rush occurred in the western foothills from 1848 through 1855. Due to inaccessibility, the range was not fully explored until 1912, the Sierra Nevada lies in Central and Eastern California, with a very small but historically important spur extending into Nevada. West-to-east, the Sierra Nevadas elevation increases gradually from 1,000 feet in the Central Valley to an height of about 10,500 feet at its crest only 50–75 miles to the east. The east slope forms the steep Sierra Escarpment, unlike its surroundings, the range receives a substantial amount of snowfall and precipitation due to orographic lift. The Sierra Nevada stretches from the Susan River and Fredonyer Pass in the north to Tehachapi Pass in the south and it is bounded on the west by Californias Central Valley and on the east by the Basin and Range Province. The geographical boundary between the Sierra and the Cascades is virtually indistinguishable, with the Fredonyer Pass designation being traditional, physiographically, the Sierra is a section of the Cascade-Sierra Mountains province, which in turn is part of the larger Pacific Mountain System physiographic division. The range is drained on its western slope by the Central Valley watershed, the northern third of the western Sierra is part of the Sacramento River watershed, and the middle third is drained by the San Joaquin River. The eastern slope watershed of the Sierra is much narrower, its rivers flow out into the endorheic Great Basin of eastern California and western Nevada. Although none of the eastern rivers reach the sea, many of the streams from Mono Lake southwards are diverted into the Los Angeles Aqueduct which provides water to Southern California, the height of the mountains in the Sierra Nevada increases gradually from north to south. Between Fredonyer Pass and Lake Tahoe, the range from 5,000 feet to more than 9,000 feet. The crest near Lake Tahoe is roughly 9,000 feet high, farther south, the highest peak in Yosemite National Park is Mount Lyell
13.
Inyo County, California
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Inyo County is a county in the U. S. state of California. As of the 2010 census, the population was 18,546, Inyo County is on the east side of the Sierra Nevada and southeast of Yosemite National Park in Central California. It contains the Owens River Valley, it is flanked to the west by the Sierra Mountains and to the east by the White Mountains, Mount Whitney, the highest peak in the Contiguous United States, is on Inyo Countys western border. The Badwater Basin in Death Valley National Park, the lowest place in North America, is in eastern Inyo County. The two points are not visible from other, but both can be observed from the Panamint Range on the west side of Death Valley, above the Panamint Valley. It has the biggest elevation difference of all of the counties, with an area of 10,192 square miles, Inyo County is the second-largest county by area in California, after San Bernardino County. Almost one-half of that area is within Death Valley National Park, however, with a population density of 1.8 people per square mile, it has the lowest population density of any county in California. Present day Inyo county has been the homeland for thousands of years of the Mono tribe, Coso people, Timbisha. They spoke the Timbisha language and the Mono language with Mono traditional narratives, the descendants of these ancestors continue to live in their traditional homelands in the Owens River Valley and in Death Valley National Park. Inyo County was formed in 1866 from the territory of the unorganized Coso County created on April 4,1864 from parts of Mono and it acquired more territory from Mono County in 1870 and Kern County and San Bernardino County in 1872. For many years it has been believed that the county derived its name from the Mono tribe of Native Americans name for the mountains in its former homeland. The local Paiutes responded that that was the land of Inyo and they meant by this that those lands belonged to the Shoshone tribe headed by a man whose name was Inyo. Indian George, a fixture of many of the stories of early Death Valley days, was Inyos son, in order to provide water needs for the growing City of Los Angeles, water was diverted from the Owens River into the Los Angeles Aqueduct in 1913. The Owens River Valley cultures and environments changed substantially, from the 1910s to 1930s the Los Angeles Department of Water and Power purchased much of the valley for water rights and control. In 1941 the Los Angeles Department of Water and Power extended the Los Angeles Aqueduct system further upriver into the Mono Basin, Inyo County is host to a number of natural superlatives. Among them are, Mount Whitney, with an elevation of 14,505 feet, is the highest point in the contiguous United States, the 12th highest peak in the U. S. and the 24th highest peak in North America. S. Census Bureau, the county has an area of 10,227 square miles. It is the second-largest county by area in California and the ninth-largest in the United States, Death Valley National Park Inyo National Forest Manzanar National Historic Site There are 22 official wilderness areas in Inyo County that are part of the National Wilderness Preservation System
14.
Amargosa Range
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The Amargosa Range is a mountain range in Inyo County, California and Nye County, Nevada. The 110-mile range runs along most of the side of Californias Death Valley. The U-shaped Amargosa River flows clockwise around the perimeter of the range, the mountain range is named after the Amargosa River, so-named for the Spanish word for bitter because of the bitter taste of the water. In order from north to south, the Grapevine Mountains, the Funeral Mountains, many of Death Valley National Parks most well-known features, such as Zabriskie Point and Artists Drive are located in or are part of the Amargosa Range
15.
Panamint Range
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The Panamint Range is a short rugged fault-block mountain range in the northern Mojave Desert, within Death Valley National Park in Inyo County, eastern California. The origin of the name is the Paiute word Panümünt, the range runs north-south for approximately 100 miles through Inyo County, forming the western wall of Death Valley and separating it from the Panamint Valley to the west. The range is part of the Basin and Range Province, at the end of the Great Basin. The highest peak in the range is Telescope Peak, with an elevation of 11,049 feet, dantes View east of Death Valley is another. The Panamint Mining District is on the side of the Panamint Range. Panamint City was a town in the district, formerly in the central section of the range. The historic mining community of Ballarat, also in the district, is now a ghost town, the Gold Hill Mining District was in the southwestern section of the range, at the northeast end of Butte Valley. The Wildrose Charcoal Kilns are ruins of charcoal kilns located near Wildrose Canyon in the northern range and they were built in 1877 by the Modock Consolidated Mining Company, to provide fuel for smelters near their lead and silver mines in the Argus Range
16.
Grapevine Mountains
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The Grapevine Mountains are a mountain range located along the border of Inyo County, California and Nye County, Nevada in the United States. The mountain range is about 22 miles long and lies in a northwest-southeasterly direction along the Nevada-California state line, the range reaches an elevation of 8,738 feet at Grapevine Peak, near Phinney Canyon on the Nevada side. Daylight Pass is at the end of the range. Most of the Grapevine Mountain chain is in Death Valley National Park, Mountain ranges of the Mojave Desert
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Owlshead Mountains
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The Owlshead Mountains are located at the southern end of Death Valley National Park near the border of the Fort Irwin Military Reservation in San Bernardino County, California, USA. The range lies in the Mojave Desert, north of the Granite Mountains, the Greenwater Range is to the northeast, the Slate Range is west, and the Kingston Range east. The mean annual precipitation in the range is five inches or less, the Owlshead Mountains are arranged in a semi-circular pattern, with the Amargosa River lying to the north. The Owlshead Mountains are primarily known for the scenic canyons found within the range that are made up of Decomposed granite, visitation to these canyons is somewhat limited due to the remote location of the Owlshead Mountains and the long distances required to reach the canyons by hiking. Within the range there are three usually dry playa lake beds -- Owl Lake, Lost Lake, and Wingate Lake, topoZone, Owlshead Mountains interactive map and more Mountain ranges of the Mojave Desert Epsom Salts Monorail
18.
Telescope Peak
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Telescope Peak is the highest point within Death Valley National Park, in the U. S. state of California. It is also the highest point of the Panamint Range, from atop this desert mountain one can see for over one hundred miles in many directions, including west to Mount Whitney, and east to Charleston Peak. The mountain was named for the great distance visible from the summit, Telescope Peak is also notable for having one of the greatest vertical rises above local terrain of any mountain in the contiguous United States. Its summit rises 11,331 feet above the lowest point in Death Valley, Badwater Basin at −279 feet, in about 15 miles and this is comparable to the rises of other tall, but better known, U. S. peaks. It is even somewhat comparable to the rise of Mount Everest above its base on the Tibetan Plateau. However Everest rises much more, and much more steeply, above its base in Nepal. Since it is the point of a range surrounded by low basins, Telescope Peak also has a particularly high topographic prominence of 6,168 feet. A variety of trees can be found on the mountain, including single-leaf pinyon, limber pine, and, at the highest elevations, from Ridgecrest, California State Route 178 leads northeast into Death Valley National Park. The road turns to unpaved about 50 miles later as it loses its highway status and it winds up through Wildrose Canyon up to a parking lot where the trail for the summit starts. The section from the Charcoal Kilns can be rough and might only be suitable for 4-wheel-drive cars with high clearance, hiking Telescope Peak by the normal route involves a 14 miles round trip hike. The trail starts in the part of Death Valley National Park at Mahogany Flat campground. The trail slowly winds itself up to the summit 7 miles later at a gradient of roughly 8%. The standard route is maintained by the National Park Service, and this route leaves directly from the Mahogany Flat Campground, and travels approximately two miles to Arcane Meadows. From Arcane Meadows, the trail winds five more miles gradually up toward Telescope Peak and this route can also be used to access two nearby peaks, Bennett Peak and Rogers Peak, a traverse that adds on minimal extra mileage. An established, but more advanced, climbing route is from Shortys Well to the summit of Telescope Peak at 11,049 feet and this route is approximately 30 to 34 miles round trip and provides a net gain of elevation of approximately 11,311 feet. The route begins at the intersection of the West Side Road, for 6.5 miles, the route climbs out of the Badwater basin and into Hanaupah Canyon. Approximately 1.5 miles after reaching the end of the road, the trail leads directly to Hanaupah Spring, at the spring, the route then turns directly north onto a scree/talus slope. Although this slope may look difficult to ascend, this is the correct way, climbers should find the best route possible up the slope
19.
Geology of the Death Valley area
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The oldest rocks in the area that now includes Death Valley National Park are extensively metamorphosed by intense heat and pressure and are at least 1700 million years old. These rocks were intruded by a mass of granite 1400 Ma, rifting thinned huge roughly linear parts of the supercontinent Rodinia enough to allow sea water to invade and divide its landmass into component continents separated by narrow straits. A passive margin developed on the edges of these new seas in the Death Valley region, carbonate banks formed on this part of the two margins only to be subsided as the continental crust thinned until it broke, giving birth to a new ocean basin. An accretion wedge of sediment then started to accumulate at the base of the submerged precipice. These sandy mudflats gave way about 550 Ma to a platform which lasted for the next 300 million years of Paleozoic time. Erosion over many millions of years created a relatively featureless plain, stretching of the crust under western North America started around 16 Ma and is thought to be caused by upwelling from the subducted spreading-zone of the Farallon Plate. This process continues into the present and is thought to be responsible for creating the Basin, by 2 to 3 million years ago this province had spread to the Death Valley area, ripping it apart and creating Death Valley, Panamint Valley and surrounding ranges. These valleys partially filled with sediment and, during colder periods during the current ice age, Lake Manly was the largest of these lakes, it filled Death Valley during each glacial period from 240,000 years ago to 10,000 years ago. By 10,500 years ago these lakes were increasingly cut off from glacial melt from the Sierra Nevada, starving them of water and concentrating salts, the desert environment seen today developed after these lakes dried up. Little is known about the history of the oldest exposed rocks in the due to extensive metamorphism. This somber, gray, almost featureless crystalline complex is composed of sedimentary and igneous rocks with large quantities of quartz. The original rocks were transformed to contorted schist and gneiss, making their original parentage almost unrecognizable, radiometric dating gives an age of 1700 million years for the metamorphism, placing it in the early part of the Proterozoic eon. A mass of granite now in the Panamint Mountains intruded this complex 1400 mya, pegmatic dikes and other widely spaced plutons of granite are also in the complex. Outcrops can be seen along the front of the Black Mountains in Death Valley and in the Talc, when the granite was being intruded, the west coast of North America ran through Eastern California and through an embayment that spread toward the Las Vegas Valley. This embayment, called the Amargosa aulacogen, had highlands north and south of it and was the result of a failed rift, many thousands of feet of sediment filled the slowly subsiding basin. Next, the metamorphosed Precambrian basement rocks were uplifted and a nearly 500-million-year-long gap in the geologic record, the Pahrump Group of formations were deposited from 1200 to 800 mya in the Amargosa aulacogen. This was after uplift-associated erosion removed whatever rocks covered the Proteozoic Complex, Pahrump is composed of, from oldest to youngest, Crystal Springs Formation, Beck Spring Dolomite, Kingston Peak Formation. Outcrops of this group can be seen in a metamorphosed belt that extends from the Panamint Mountains to the eastern part of the Kingston Range
20.
Sentinel-2
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It consists of two identical satellites, Sentinel-2A and Sentinel-2B. At high latitudes, Sentinel-2 swath overlap and some regions will be observed twice or more every 5 days, the planned orbit is Sun synchronous at 786 km altitude,14.3 revolutions per day, with a 10,30 a. m. descending node. This local time was selected as a compromise between minimizing cloud cover and ensuring suitable Sun illumination and it is close to the Landsat local time and matches SPOTs, allowing the combination of Sentinel-2 data with historical images to build long-term time series. The two satellites will work on opposite sides of the orbit, the launch of the first satellite, Sentinel-2A, occurred 23 June 2015 at 01,52 UTC on a Vega launch vehicle. Sentinel-2B was launched on 7 March 2017 at 01,49 UTC, the Sentinel-2 satellites will each carry a single multi-spectral instrument with 13 spectral channels in the visible/near infrared and short wave infrared spectral range. It has a 150 mm aperture and a three-mirror anastigmat design with a length of about 600 mm. The mirrors are rectangular and made of carbide, a similar technology to those on the Gaia mission. Sentinel-2 will serve a range of applications related to Earths land surface. The mission will provide information for agricultural and forestry practices. Satellite images will be used to various plant indices such as leaf area chlorophyll. This is particularly important for effective yield prediction and applications related to Earth’s vegetation, as well as monitoring plant growth, Sentinel-2 can be used to map changes in land cover and to monitor the worlds forests. It will also provide information on pollution in lakes and coastal waters, images of floods, volcanic eruptions and landslides contribute to disaster mapping and help humanitarian relief efforts. Sentinel-2s multi-spectral imager undertakes systematic acquisition in a single observation mode, Level-1B, Top of atmosphere radiances in sensor geometry. Level-1B is composed of granules, one represents the sub-image one of the 12 detectors in the across track direction. Each Level-1B granule has a volume of approximately 27 MB. Level-1B products require expert knowledge of orthorectification techniques, level-1C, Top of atmosphere reflectances in fixed cartographic geometry. Level-1C images are a set of tiles of 100 km2, each of which is approximately 500 MB and these products contain applied radiometric and geometric corrections. Level-2A, Bottom of atmosphere reflectances in cartographic geometry and this product is currently processed on the user side by using a processor running on ESA’s Sentinel-2 Toolbox
21.
Satellite imagery
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Satellite imagery consists of images of Earth or other planets collected by satellites. Imaging satellites are operated by governments and businesses around the world, Satellite imaging companies sell images under licence. Images are licensed to governments and businesses such as Apple Maps, the first images from space were taken on sub-orbital flights. The U. S-launched V-2 flight on October 24,1946 took one image every 1.5 seconds. With an apogee of 65 miles, these photos were from five times higher than the previous record, the first satellite photographs of Earth were made on August 14,1959 by the U. S. The first satellite photographs of the Moon might have made on October 6,1959 by the Soviet satellite Luna 3. The Blue Marble photograph was taken from space in 1972, and has very popular in the media. Also in 1972 the United States started the Landsat program, the largest program for acquisition of imagery of Earth from space, Landsat Data Continuity Mission, the most recent Landsat satellite, was launched on 11 February 2013. In 1977, the first real time satellite imagery was acquired by the United Statess KH-11 satellite system, all satellite images produced by NASA are published by NASA Earth Observatory and are freely available to the public. Several other countries have satellite imaging programs, and a collaborative European effort launched the ERS, there are also private companies that provide commercial satellite imagery. Images can be in visible colours and in other spectra, there are also elevation maps, usually made by radar images. Interpretation and analysis of imagery is conducted using specialized remote sensing applications. There are four types of resolution when discussing satellite imagery in remote sensing, spatial, spectral, temporal, and radiometric. GSD is a term containing the optical and systemic noise sources and is useful for comparing how well one sensor can see an object on the ground within a single pixel. For example, the GSD of Landsat is ~30m, which means the smallest unit that maps to a single pixel within an image is ~30m x 30m, the latest commercial satellite has a GSD of 0.41 m. This compares to a 0.3 m resolution obtained by some early military film based Reconnaissance satellite such as Corona, the resolution of satellite images varies depending on the instrument used and the altitude of the satellites orbit. For example, the Landsat archive offers repeated imagery at 30 meter resolution for the planet, Landsat 7 has an average return period of 16 days. For many smaller areas, images with resolution as high as 41 cm can be available, Satellite imagery is sometimes supplemented with aerial photography, which has higher resolution, but is more expensive per square meter
22.
Graben
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In geology, a graben is a depressed block of the Earths crust bordered by parallel faults. Graben is German for ditch or trench, the plural form is either graben or grabens. A graben is a valley with an escarpment on each side caused by the displacement of a block of land downward. Graben often occur side-by-side with horsts, horst and graben structures indicate tensional forces and crustal stretching. Graben are produced from parallel normal faults, where the displacement of the wall is downward. The faults typically dip toward the center of the graben from both sides, horsts are parallel blocks that remain between graben, the bounding faults of a horst typically dip away from the center line of the horst. Single or multiple graben can produce a rift valley, in many rifts, the graben are asymmetric, with a major fault along only one of the boundaries, and these are known as half-graben. The polarity of the bounding faults typically alternates along the length of the rift. The asymmetry of a half-graben strongly affects syntectonic deposition, comparatively little sediment enters the half-graben across the main bounding fault because of footwall uplift on the drainage systems. The exception is at any offset in the bounding fault. Most of the sediment will enter the half-graben down the hanging wall side. S. Central Graben, North Sea Viking Graben, North Sea Fossa
23.
Fault (geology)
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In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement. Large faults within the Earths crust result from the action of tectonic forces. Energy release associated with movement on active faults is the cause of most earthquakes. A fault plane is the plane that represents the surface of a fault. A fault trace or fault line is the intersection of a plane with the ground surface. A fault trace is also the line commonly plotted on maps to represent a fault. Since faults do not usually consist of a single, clean fracture, the two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the wall occurs above the fault plane. This terminology comes from mining, when working a tabular ore body, because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. A fault in ductile rocks can also release instantaneously when the rate is too great. The energy released by instantaneous strain-release causes earthquakes, a common phenomenon along transform boundaries, slip is defined as the relative movement of geological features present on either side of a fault plane, and is a displacement vector. A faults sense of slip is defined as the motion of the rock on each side of the fault with respect to the other side. In practice, it is only possible to find the slip direction of faults. Based on direction of slip, faults can be categorized as, strike-slip. Dip-slip, offset is predominantly vertical and/or perpendicular to the fault trace, oblique-slip, combining significant strike and dip slip. The fault surface is usually vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are known as sinistral faults. Those with right-lateral motion are known as dextral faults
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Garlock Fault
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The Garlock Fault is a left-lateral strike-slip fault running approximately northeast-southwest along the north margins of the Mojave Desert of Southern California. It runs for much of its length along the base of the Tehachapi Mountains. The Garlock Fault marks the boundary of the area known as the Mojave Block, as well as the southern ends of the Sierra Nevada. Stretching for 250 kilometers, it is the second-longest fault in California and is one of the most prominent geological features in the part of the state. The Garlock Fault runs from a junction with the San Andreas Fault in the Antelope Valley and it is named after the historic mining town of Garlock, founded in 1894 by Eugene Garlock and now a ghost town. In the case of the Garlock Fault, this means that the north of the fault is moving westward relative to the terrain south of the fault. The Garlock Fault moves at a rate of between 2 and 11 mm a year, with a slip of around 7 millimeters. While most of the fault is locked, certain segments have shown to move by aseismic creep. The most recent notable event was a magnitude 5.7 near the town of Mojave on July 11,1992 and it is thought to have been triggered by the Landers earthquake, just two weeks earlier. The last significant ruptures on the Garlock were thought to be in the years 1050 AD and 1500 AD, research has pinned the interval between significant ruptures on the Garlock as being anywhere between 200 and 3,000 years depending on the segment of the fault. The Garlock Fault constitutes one of the borders of the Mojave Desert, mountain ranges mark its western edge, and its trace is clearly visible on aerial images of the state. Relatively few communities lie directly along the Garlock, as it is situated in the desert, with Frazier Park, Tehachapi, Mojave. However, a rupture along the Garlock would probably be felt in most of the southern part of California. Southern California Earthquake Data Center, Faults in Southern California USGS Database, Garlock Fault
25.
Amargosa River
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The Amargosa River is an intermittent waterway,185 miles long, in southern Nevada and eastern California in the United States. It drains a high desert region, the Amargosa Valley in the Amargosa Desert northwest of Las Vegas, into the Mojave Desert, and finally into Death Valley where it disappears into the ground aquifer. Except for a portion of its route in the Amargosa Canyon in California and a small portion at Beatty, Nevada. A 26-mile stretch of the river between Shoshone and Dumont Dunes is protected as a National Wild and Scenic River, at the south end of Tecopa Valley the Amargosa River Natural Area protects the habitat. Except during flash floods that occur after cloudbursts, most of the course of the Amargosa River is dry on the surface, the flow is generally underground except for stretches near Beatty and near Tecopa, California, in the Amargosa Canyon. In the canyon, the passes through the Amargosa River Natural Area. The river arises at about 1,200 feet above sea level in Nye County, Nevada, thirsty Canyon Wash enters at the rivers source, and when carrying water, the river flows from there southwest into Oasis Valley. Running parallel to U. S. Route 95 near the Bullfrog Hills to the west, another 3 miles or so downstream, the river flows through Beatty and turns south-southeast through the Amargosa Narrows into the Amargosa Desert. At this point, Bare Mountain lies to the left and the Grapevine, downstream of the Narrows, still flowing roughly parallel to Route 95, the river passes Big Dune, which is on the rivers left. Shortly thereafter it passes the town of Amargosa Valley on the left, leaves Nevada, in this stretch, it receives Forty Mile Wash from the left. Running roughly parallel to California Route 127, the passes through Death Valley Junction. Shortly thereafter it receives Carson Slough, which drains Ash Meadows National Wildlife Refuge, soon the river passes between the Resting Spring Range to the left and the Greenwater Range to the right before reaching Shoshone. Below Shoshone, the continues roughly parallel to Route 127 to Tecopa. Turning west, the river crosses under Route 127 and enters Death Valley National Park between the end of the Amargosa Range on the right and the Avawatz Mountains on the left. In this stretch, the river runs parallel to Harry Wade Road and, further north, to California Route 178. The river receives Willow Creek from the right and ends in Badwater Basin, about 279 feet below sea level, disappearing into the ground, it feeds the aquifer that is the remnant of prehistoric Lake Manly. The United States Geological Survey monitors the flow of the Amargosa River at a station near the Old Spanish Trail Road,0.2 miles west of Tecopa. The average flow of the river at this station is 3.80 cubic feet per second and this is from a drainage area of 3,090 square miles, much of which is noncontributing and all of which represents about 60 percent of the total Amargosa River drainage basin
26.
Salt pan (geology)
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Natural salt pans or salt flats are flat expanses of ground covered with salt and other minerals, usually shining white under the Sun. They are found in deserts, and are natural formations, a salt pan forms by evaporation of a water pool such as a lake or pond. This happens in climates where the rate of water exceeds the rate of precipitation. If the water drain into the ground, it remains on the surface until it evaporates. Over thousands of years, the minerals accumulate on the surface and these minerals reflect the Suns rays and often appear as white areas. The crust of salt can conceal a quagmire of mud that can engulf a truck, the Qattara Depression in the eastern Sahara desert contains many such traps which served as strategic barriers during World War II. The Bonneville Salt Flats in Utah, where land speed records have been set, is a well-known salt pan in the arid regions of the western United States. The Etosha pan, in the Etosha National Park in Namibia, is another prominent example of a salt pan, the Salar de Uyuni in Bolivia is the largest salt pan in the world. It contains 50%-70% of the worlds lithium reserves, dry lake Pan Sabkha Salt evaporation pond Salt lake Sink Solonchak Briere, Peter R. Playa, playa lake, sabkha, Proposed definitions for old terms. Lowenstein, Tim K. Lawrence A. Hardie, criteria for the recognition of salt-pan evaporites
27.
Pleistocene
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The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the worlds most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period, the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, all of these stages were defined in southern Europe. In addition to this subdivision, various regional subdivisions are often used. Charles Lyell introduced the term pleistocene in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today and this distinguished it from the older Pliocene Epoch, which Lyell had originally thought to be the youngest fossil rock layer. The Pleistocene has been dated from 2.588 million to 11,700 years before present and it covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9640 BC, the IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75°06 N 42°18 W, the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils, Discoaster pentaradiatus, the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. The revised definition of the Quaternary, by pushing back the date of the Pleistocene to 2.58 Ma. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places and it is estimated that, at maximum glacial extent, 30% of the Earths surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the sheet, a few hundred kilometres in North America. The mean annual temperature at the edge of the ice was −6 °C, during interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global, antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap, there were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one, the Cordilleran ice sheet covered the North American northwest, the east was covered by the Laurentide
28.
Lake Manly
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Lake Manly is a former pluvial lake in Death Valley, California. The lake formerly covered much of Death Valley with an area of 1,600 square kilometres during the so-called Blackwelder stand. The lake received water mainly from the Amargosa River and at various points from the Mojave River, the lake and its substantial catchment favoured the spread of a number of aquatic species, the spread of some lizards, pupfish and springsnails was aided by its waters. A number of diatoms developed in the lake, which supported a substantial ecosystem. Lake Manly existed during different times in the geological past, after the drying of this lake a later lake stage occurred 35,000 -10,000 years ago during the Tioga/Wisconsin glaciation, this lake was smaller than the Blackwelder lake. During the Holocene, the disappeared, today only ephemeral lakes occur in Death Valley during strong floods. Lake Manly is one among many major lakes that formed in the Great Basin, Lake Manly collected the overflow from a number of lakes including Lake Tecopa, Mono Lake, Lake Owens, Searles Lake, Lake Panamint, Lake Mojave, Lake Dumont and Lake Manix. Not all of them existed or drained into Lake Manly simultaneously, the formation of Lake Manly was caused by decreasing temperatures and hence decreasing evaporation as well as increased precipitation during the ice ages. Other lake systems in the Great Basin expanded due to the causes as well. The lake was named in honour of William Lewis Manly, Manly in 1849 rescued white immigrants from Death Valley. The name Lake Rogers for a potential northern lake in Death Valley was derived from a compatriot of Manly, the name Lake Manly was coined in 1932, and is sometimes spelled as Manley, which is a misspelling. Other names for the lakes in Death Valley are Death Valley Pleistocene lakes and Death Valley Lake, the existence of a lake in Death Valley in the past was also considered during that time, although it was at first not universally accepted that it had been a large lake. The first evidence for it to have been a lake was described in 1924 by Levi F. Noble. Already before in 1890 did Grove Karl Gilbert assume a lake had existed in Death Valley, while the deposits were once attributed to a single lake stand, later evidence of various lake cycles going back to the Pliocene was found. The history of Lake Manly is not as well understood as that of Lake Lahontan and Lake Bonneville, more recently, the fact that Lake Manly formerly drained the area of Yucca Mountain, a proposed nuclear waste repository, has lead to renewed scientific interest. The Badwater Basin is the deepest point in North America, Death Valley started to form about 14 million years ago, and by the Pliocene it was well developed. The valley is kept deep by vertical faulting, which is faster here than anywhere else in the US, various types of rocks form the surface areas of Death Valley, some going back as far as the Precambrian. Thus, shorelines from the lake stands are often not at the same altitude in various parts of the basin
29.
Borax
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Soid Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. Powdered borax is white, consisting of colorless crystals that dissolve easily in water. Borax has a variety of uses. It is a component of many detergents, cosmetics, and enamel glazes, in artisanal gold mining, the borax method is sometimes used as a substitute for toxic mercury in the gold extraction process. Borax was reportedly used by miners in parts of the Philippines in the 1900s. The term borax is used for a number of closely related minerals or chemical compounds that differ in their water content. Commercially sold borax is partially dehydrated, Borax was first discovered in dry lake beds in Tibet and was imported via the Silk Road to the Arabian Peninsula in the 8th Century AD. However, it is formulated as Na2·8H2O, since borax contains the 2− ion. In this structure, there are two four-coordinate boron atoms and two boron atoms. Borax is also converted to boric acid and other borates. When borax is added to a flame, it produces a green color. Borax is not used for purpose in fireworks due to the overwhelming yellow color of sodium. Boric acid is used to color methanol flames a transparent green, the English word borax is Latinized, the Middle English form was boras, from Old French boras, bourras. That may have been from medieval Latin baurach, borac, borax, or maybe directly from the Arabic, along with Spanish borrax and Italian borrace, the Arabic was بورق bauraq/bwrk, a word also used for borax. Traditional Arabic dictionaries say that it derives from the verb to glisten, which is also written بورق bwrq, but it seems to actually derive from the Persian būrah. The word borax is found in Arabic būraq, meaning white, which is from Middle Persian bwrk, another name for borax is tincal, from Sanskrit. The word tincal /ˈtɪŋkəl/ tinkle, or tincar /ˈtɪŋkər/ tinker, refers to crude borax, before it is purified, as mined from deposits in Tibet, Persia. The word was adopted in the 17th century from Malay tingkal and from Urdu/Persian/Arabic تنکار tinkār/tankār and these all appear to be related to the Sanskrit टांकण ṭānkaṇa
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Subtropics
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The subtropics are geographic and climate zones located roughly between the tropic circle of latitude at 23.5 latitude and temperate latitudes. Subtropical climates are characterized by warm to hot summers and cool to mild winters with infrequent frost. Subtropical climates can occur at elevations within the tropics, such as in the southern end of the Mexican Plateau and in Vietnam. Six climate classifications use the term to define the various temperature. A great portion of the deserts are located within the subtropics. Within savanna regimes in the subtropics, a wet season is seen annually during the summer, within Mediterranean climate regimes, the wet season occurs during the winter. Areas bordering warm oceans are prone to heavy rainfall from tropical cyclones. Plants such as palms, citrus, mango, lychee, the tropics have been historically defined as lying between the Tropic of Cancer and Tropic of Capricorn, located at 23. 45° north and south latitude respectively. The poleward fringe of the subtropics is located at approximately 40° north and south latitude respectively, northern fringes of the type can go further north due to moderating effects of ocean streams, like in parts of Southern Europe due to heat transported by the Gulf Stream. Several methods have used to define the subtropical climate. In the Trewartha climate classification, a subtropical region should have at least eight months with a temperature greater than 10 °C. According to the Troll-Paffen climate classification, there exists one large subtropical zone named the warm-temperate subtropical zone. According to the E. Neef climate classification, the zone is divided into two parts, Rainy winters of the west sides and Eastern subtropical climate. According to the Wilhelm Lauer & Peter Frankenberg climate classification, the zone is divided into three parts, high-continental, continental, and maritime. According to the Siegmund/Frankenberg climate classification, subtropical is one of six zones in the world. Heating of the earth near the equator leads to large amounts of upward motion and convection along the trough or Intertropical convergence zone. The upper-level divergence over the near-equatorial trough leads to air rising and moving away from the equator aloft, as the air moves towards the Mid-Latitudes, it cools and sinks, which leads to subsidence near the 30th parallel of both hemispheres. This circulation is known as the Hadley cell and leads to the formation of the subtropical ridge, many of the worlds deserts are caused by these climatological high-pressure areas, located within the subtropics
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Desert climate
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An area that features this climate usually experiences from 25 to 200 mm per year of precipitation and in some years may experience no precipitation at all. Averages may be even less such as in Arica, Chile, there are usually two or three variations of a desert climate, a hot desert climate, a cold desert climate and, sometimes, a mild desert climate. To determine whether a location has a climate, the precipitation threshold is determined. If the areas precipitation is less than half the threshold. Hot desert climates are found under the subtropical ridge where there is largely unbroken sunshine for the whole year due to the stable descending air. These areas are located between 30 degrees south and 30 degrees north latitude, under the subtropical latitudes called the horse latitudes, hot desert climates are generally hot, sunny and dry year-round. Hot desert climates also reach similar latitudes in the Middle East, North Africa, hot desert climates usually feature hot, sometimes exceptionally hot, periods of the year. In many locations featuring a hot climate, maximum temperatures of over 40 °C are not uncommon in summer. The world absolute heat records, over 50 °C, are generally in the hot deserts, some desert locations consistently experience very high temperatures all year long, even during wintertime. These locations feature some of the highest annual average temperatures recorded on Earth and this last feature is seen in some parts of deserts of Africa and Arabia. During colder periods of the year, night-time temperatures can drop to freezing or below due to the radiation loss under the clear skies. However, very rarely do temperatures drop far below freezing, only one region in Europe has a hot desert climate, Province of Almeria, Province of Alicante and Province of Murcia in South Eastern Spain. Cold desert climates usually feature warm and dry summers, though summers typically are not quite as hot as summers in hot desert climates, unlike hot desert climates, cold desert climates tend to feature cold winters with rare snow. Cold desert climates are found at higher altitudes than hot desert climates. A cold desert climate is found in temperate zones, usually in the rain shadow of high mountains. A classic example of this is the Patagonian Desert in Argentina bounded by the Andes to its west, in the case of Central Asia, mountains restrict precipitation from the monsoon. The Gobi desert in Mongolia is an example of this. Though hot in summer, it shares the cold winters of the rest of Central Asia
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Greenhouse effect
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The greenhouse effect is the process by which radiation from a planets atmosphere warms the planets surface to a temperature above what it would be without its atmosphere. If a planets atmosphere contains radiatively active gases the atmosphere radiate energy in all directions. Part of this radiation is directed towards the surface, warming it, greenhouse gases in the atmosphere radiate energy, some of which is directed to the surface and lower atmosphere. The mechanism that produces this difference between the surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect. Earth’s natural greenhouse effect is critical to supporting life, human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming. The mechanism is named after a faulty analogy with the effect of radiation passing through glass. The way a greenhouse retains heat is fundamentally different, as a works by reducing airflow. The existence of the effect was argued for by Joseph Fourier in 1824. The effect was more fully quantified by Svante Arrhenius in 1896, however, the term greenhouse was not used to refer to this effect by any of these scientists, the term was first used in this way by Nils Gustaf Ekholm in 1901. Earth receives energy from the Sun in the form of ultraviolet, visible, of the total amount of solar energy available at the top of the atmosphere, about 26% is reflected to space by the atmosphere and clouds and 19% is absorbed by the atmosphere and clouds. Most of the energy is absorbed at the surface of Earth. Because the Earths surface is colder than the photosphere of the Sun, most of this thermal radiation is absorbed by the atmosphere, thereby warming it. In addition to the absorption of solar and thermal radiation, the atmosphere gains heat by sensible, the atmosphere radiates energy both upwards and downwards, the part radiated downwards is absorbed by the surface of Earth. This leads to an equilibrium temperature than if the atmosphere were absent. An ideal thermally conductive blackbody at the distance from the Sun as Earth would have a temperature of about 5.3 °C. However, because Earth reflects about 30% of the incoming sunlight, the surface temperature of this hypothetical planet is 33 °C below Earths actual surface temperature of approximately 14 °C. The basic mechanism can be qualified in a number of ways, the atmosphere near the surface is largely opaque to thermal radiation, and most heat loss from the surface is by sensible heat and latent heat transport. Radiative energy losses become increasingly important higher in the atmosphere, largely because of the concentration of water vapor
33.
Convection oven
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A convection oven is an oven that has fans to circulate air around food. The earliest use of a fan in a domestic oven dates from dates by the Malleable Iron Range Company. A convection oven has a fan with a heating element around, a small fan circulates the air in the cooking chamber. Convection ovens may include radiant heat sources at the top and bottom of the oven, on the other hand, some ovens have all the heating elements placed in an outside enclosure and hidden from the food. A convection oven allows a reduction in cooking temperature compared to a conventional oven and this comparison will vary, depending on factors including, for example, how much food is being cooked at once or if airflow is being restricted by using an oversized baking tray. Product testing has not demonstrated that convection cooking within a toaster oven results in notable advantages to toasting or baking, another form of a convection oven is called an impingement oven. This type of oven is used to cook pizzas in restaurants. Impingement ovens have a flow rate of hot air from both above and below the food. The air flow is directed onto food that passes through the oven on a conveyor belt. Impingement ovens can achieve a higher heat transfer than a conventional oven. There are convection microwave ovens which combine a convection oven with an oven to cook food with the speed of a microwave oven
34.
Virga
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In meteorology, virga is an observable streak or shaft of precipitation that falls from a cloud but evaporates or sublimates before reaching the ground. A shaft of precipitation which does not evaporate before reaching the ground is a precipitation shaft and it is very common in the desert and in temperate climates. In North America, it is seen in the Western United States. It is also common in the Middle East, Australia. Virga can cause varying effects, because as rain is changed from liquid to vapor form. Precipitation falling into these cooling down drafts may eventually reach the ground, in some instances, these pockets of colder air can descend rapidly, creating a wet or dry microburst which can be extremely hazardous to aviation. Conversely, precipitation evaporating at high altitude can compressionally heat as it falls and this fairly rare phenomenon, a heat burst, also tends to be of exceedingly dry air. The word is derived from Latin virga meaning twig or branch, sulfuric acid rain in the atmosphere of Venus evaporates before reaching the ground due to the high heat near the surface. Similarly, virga happens on gas giant planets such as Jupiter, in September 2008 NASAs Phoenix lander discovered a snow variety of virga falling from Martian clouds. Aviation safety Cavum Precipitation shaft Sun pillar National Science Digital Library - Virga Viewing the Vagaries and Verities of Virga Alistair B, fraser and Craig F. Bohren, Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania,2 November 1992 and 25 January 1993
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Rain shadow
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A rain shadow is a dry area on the leeward side of a mountainous area. The mountains block the passage of rain-producing weather systems and cast a shadow of dryness behind them, wind and moist air is drawn by the prevailing winds towards the top of the mountains, where it condenses and precipitates before it crosses the top. The air, without much moisture left, advances behind the mountains creating a side called the rain shadow. The condition exists because warm moist air rises by orographic lifting to the top of a mountain range, as atmospheric pressure decreases with increasing altitude, the air has expanded and adiabatically cooled to the point that the air reaches its adiabatic dew point. At the adiabatic dew point, moisture condenses onto the mountain and it precipitates on the top, the air descends on the leeward side, but due to the precipitation it has lost much of its moisture. There are regular patterns of prevailing winds found in round the Earths equatorial region. The zone designated the trade winds is the zone between about 30° N and 30° S, blowing predominantly from the northeast in the Northern Hemisphere, the strongest westerly winds in the middle latitudes can come in the Roaring Forties between 30 and 50 degrees latitude. The Dasht-i-Lut in Iran is in the shadow of the Elburz. The Ordos Desert is rain shadowed by mountain chains including the Kara-naryn-ula, the Sheitenula, and the Yin Mountains, which link on to the south end of the Great Khingan Mountains. The Thar desert is bounded and rain shadowed by the Aravalli ranges to the south-east, the Himalaya to the northeast, Eastern Side of Sahyadri ranges on Deccan e. g. Northern Karnataka & Solapur, Beed, Osmanabad and Vidharba Plateau of India. The central region of Myanmar is in the shadow of the Arakan Mountains and is almost semi-arid with only 750 millimetres of rain as against as much as 5.5 metres on the Rakhine State coast. The High Peaks of Mount Lebanon rain-shadow the northern parts of the Beqaa Valley, the Judean Desert, the Dead Sea and the western slopes of the Moab Mountains on the opposite side are rain-shadowed by the Judean Hills. The Atacama Desert in Chile is the driest non-polar desert on Earth because it is blocked from moisture on both sides, Cuyo and Eastern Patagonia is rain shadowed from the prevailing westerly winds by the Andes range and is arid. The Argentinian wine region of Cuyo and Northern Patagonia is almost completely dependent on irrigation, on the largest scale, the entirety of the North American Interior Plains are shielded from the prevailing Westerlies carrying moist Pacific weather by the North American Cordillera. More pronounced effects are observed, however, in valley regions within the Cordillera. Most rainshadows in the western United States are due to the Sierra Nevada, champlain Valley in upstate New York. It is protected by the Adirondack Mountains, hawaii also has rain shadows, with some areas being desert. Orographic lifting produces the worlds second-highest annual precipitation record,12.7 meters, on the island of Kauai, the entire island of Kahoolawe lies in the rain shadow of Mauis East Maui Volcano
36.
Oman
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Oman, officially the Sultanate of Oman, is an Arab country on the southeastern coast of the Arabian Peninsula. The coast is formed by the Arabian Sea on the southeast, the Madha and Musandam exclaves are surrounded by the UAE on their land borders, with the Strait of Hormuz and Gulf of Oman forming Musandams coastal boundaries. From the late 17th century, the Omani Sultanate was an empire, vying with Portugal and Britain for influence in the Persian Gulf. At its peak in the 19th century, Omani influence or control extended across the Strait of Hormuz to modern-day Iran and Pakistan, as its power declined in the 20th century, the sultanate came under the influence of the United Kingdom. Historically, Muscat was the trading port of the Persian Gulf region. Muscat was also among the most important trading ports of the Indian Ocean, the Sultan Qaboos bin Said al Said has been the hereditary leader of the country since 1970. Sultan Qaboos is the current ruler in the Middle East. Oman has modest oil reserves, ranking 25th globally, nevertheless, in 2010 the UNDP ranked Oman as the most improved nation in the world in terms of development during the preceding 40 years. A significant portion of its economy is tourism and trade of fish, dates and this sets it apart from its neighbors solely oil-dependent economies. Oman is categorized as an economy and ranks as the 74th most peaceful country in the world according to the Global Peace Index. Two optically stimulated luminescence age estimates place the Arabian Nubian Complex at 106,000 years old and this supports the proposition that early human populations moved from Africa into Arabia during the Late Pleistocene. Dereaze, located in the city of Ibri, is the oldest known settlement in the area. Archaeological remains have been discovered here from the Stone Age and the Bronze Age, findings have included stone implements, animal bones, shells and fire hearths, with the latter dating back to 7615 BC as the oldest signs of human settlement in the area. Other discoveries include hand-molded pottery bearing distinguishing pre-Bronze Age marks, heavy flint implements, pointed tools, sumerian tablets refer to a country called Magan or Makan, a name believed to refer to Omans ancient copper mines. Mazoon, another used for the region, is derived from the word muzn. The present-day name of the country, Oman, is believed to originate from the Arab tribes who migrated to its territory from the Uman region of Yemen. Many such tribes settled in Oman, making a living by fishing, herding or stock breeding, from the 6th century BC to the arrival of Islam in the 7th century AD, Oman was controlled and/or influenced by three Persian dynasties, the Achaemenids, Parthians and Sassanids. A few scholars believe that in the 6th century BC, the Achaemenids exerted a strong degree of control over the Omani peninsula, Central Oman has its own indigenous so-called Late Iron Age cultural assemblage, the Samad al-Shan
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Lake
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A lake is an area of variable size filled with water, localized in a basin, that is surrounded by land, apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, and therefore are distinct from lagoons, Lakes can be contrasted with rivers or streams, which are usually flowing. Most lakes are fed and drained by rivers and streams, natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers, in some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will fill in with sediments or spill out of the basin containing them. The word lake comes from Middle English lake, from Old English lacu, from Proto-Germanic *lakō, cognates include Dutch laak, Middle Low German lāke as in, de, Moorlake, de, Wolfslake, de, Butterlake, German Lache, and Icelandic lækur. Also related are the English words leak and leach, none of these definitions completely excludes ponds and all are difficult to measure. For this reason, simple size-based definitions are used to separate ponds. One definition of lake is a body of water of 2 hectares or more in area, however, others have defined lakes as waterbodies of 5 hectares and above, or 8 hectares and above. Charles Elton, one of the founders of ecology, regarded lakes as waterbodies of 40 hectares or more. The term lake is used to describe a feature such as Lake Eyre. In common usage, many bear names ending with the word pond. One textbook illustrates this point with the following, In Newfoundland, for example, almost every lake is called a pond, whereas in Wisconsin, the majority of lakes on Earth are fresh water, and most lie in the Northern Hemisphere at higher latitudes. Canada, with a drainage system has an estimated 31,752 lakes larger than 3 square kilometres and an unknown total number of lakes. Finland has 187,888 lakes 500 square metres or larger, most lakes have at least one natural outflow in the form of a river or stream, which maintain a lakes average level by allowing the drainage of excess water. Some lakes do not have an outflow and lose water solely by evaporation or underground seepage or both. Many lakes are artificial and are constructed for power generation, aesthetic purposes, recreational purposes, industrial use. Globally, lakes are greatly outnumbered by ponds, of an estimated 304 million standing water bodies worldwide, 91% are 1 hectare or less in area
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Precipitation
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In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, snow, graupel, Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and precipitates. Thus, fog and mist are not precipitation but suspensions, because the vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated, Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers, moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is active when freezing rain is occurring. A stationary front is often present near the area of freezing rain, provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. Eventually, the droplets will grow large enough to form raindrops. Lake-effect snowfall can be locally heavy, thundersnow is possible within a cyclones comma head and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation, on the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. The movement of the trough, or intertropical convergence zone. Precipitation is a component of the water cycle, and is responsible for depositing the fresh water on the planet. Approximately 505,000 cubic kilometres of water falls as precipitation each year,398,000 cubic kilometres of it over the oceans and 107,000 cubic kilometres over land. Given the Earths surface area, that means the globally averaged annual precipitation is 990 millimetres, Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Precipitation may occur on celestial bodies, e. g. when it gets cold, Mars has precipitation which most likely takes the form of frost. Precipitation is a component of the water cycle, and is responsible for depositing most of the fresh water on the planet. Approximately 505,000 km3 of water falls as precipitation each year,398,000 km3 of it over the oceans, given the Earths surface area, that means the globally averaged annual precipitation is 990 millimetres. Mechanisms of producing precipitation include convective, stratiform, and orographic rainfall, Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice
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Sunshine duration
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It is a general indicator of cloudiness of a location, and thus differs from insolation, which measures the total energy delivered by sunlight over a given period. Sunshine duration is usually expressed in hours per year, or in hours per day, the first measure indicates the general sunniness of a location compared with other places, while the latter allows for comparison of sunshine in various seasons in the same location. Another often-used measure is percentage ratio of recorded bright sunshine duration, an important use of sunshine duration data is to characterize the climate of sites, especially of health resorts. This also takes account the psychological effect of strong solar light on human well-being. It is often used to promote tourist destinations, if the Sun were to be above the horizon 50% of the time for a standard year consisting of 8,760 hours, apparent maximal daytime duration would be 4,380 hours for any point on Earth. However, there are physical and astronomical effects that change that picture, namely, atmospheric refraction allows the Sun to be still visible even when it physically sets below the horizon. For that reason, average daytime is longest in polar areas, places on the Arctic Circle have the longest total annual daytime,4,647 hours, while the North Pole receives 4,575. Because of elliptic nature of the Earths orbit, the Southern Hemisphere is not symmetrical, the Equator has a total daytime of 4,422 hours per year. Given the theoretical maximum of daytime duration for a given location, bright sunshine hours represent the total hours when the sunlight is stronger than a specified threshold, as opposed to just visible hours. Visible sunshine, for example, occurs around sunrise and sunset, measurement is performed by instruments called sunshine recorders. For the specific purpose of sunshine duration recording, Campbell–Stokes recorders are used, when the intensity exceeds a pre-determined threshold, the tape burns. The total length of the trace is proportional to the number of bright hours. Another type of recorder is the Jordan sunshine recorder, newer, electronic recorders have more stable sensitivity than that of the paper tape. In 2003, the duration was finally defined as the period during which direct solar irradiance exceeds a threshold value of 120 W/m². The sky is clear in these regions, and fair weather is virtually perpetual, the descending branch of the Hadley cell and the long-term lack of atmospheric disturbances helps to explain the seemingly endless supply of sunny, cloud-free days in the deserts. Low clouding conditions are associated with rainfall shortage, as seen in these dry regions. In the belt encompassing northern Chad and the Tibesti Mountains, northern Sudan, southern Libya, some places in the interior of the Arabian Peninsula receive 3, 600–3,800 hours of bright sunshine annually. The largest sun-baked region in the world is North Africa, the sunniest month in the world is December in Eastern Antarctica, with almost 23 hours of bright sun daily
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Landsat 5
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Landsat 5 was a low Earth orbit satellite launched on March 1,1984 to collect imagery of the surface of Earth. A continuation of the Landsat Program, Landsat 5 was jointly managed by the U. S. Geological Survey, data from Landsat 5 was collected and distributed from the USGSs Center for Earth Resources Observation and Science. After 29 years in space, Landsat 5 was officially decommissioned on June 5,2013, near the end of its mission, Landsat 5s use was hampered by equipment failures, and it was largely superseded by Landsat 7 and Landsat 8. Mission scientists anticipated the satellite will re-enter Earths atmosphere and disintegrate around 2034, Landsat 5 had a maximum transmission bandwidth of 85 Mbit/s. It was deployed at an altitude of 705.3 km, the satellite was an identical copy of Landsat 4 and was originally intended as a backup. Therefore, Landsat 5 carried the instruments, including the Thematic Mapper. The Multi-Spectral Scanner was powered down in 1995, but reactivated again in 2012, Landsat 5 was launched by NASA from Vandenberg Air Force Base on March 1,1984. Landsat 5 recorded many significant events and it was the first satellite to capture the nuclear accident at Chernobyl in 1986. Landsat 5 also documented deforestation occurring in regions, and captured the devastating 2004 tsunami in southeast Asia. On November 26,2005, the solar array drive on Landsat 5 began exhibiting unusual behavior. The solar array drive maintains the proper pointing angle between the array and the Sun. The rotation of the array drive became sporadic, and the solar array was not able to provide the power needed to charge the batteries. Maintaining power to the batteries is critical to proper operation of the spacecraft. The primary solar array drive failed under similar circumstances in January 2006, as a result of this situation, imaging operations were suspended. After a month-long investigation in December 2005 and testing in January 2006, on December 18,2009, the transmitter on Landsat 5 experienced technical difficulties. Data downlink was restored on January 7,2010 after a test successfully managed to retrieve a picture over North America and this test exercised the only remaining Traveling Wave Tube Amplifier. The remaining TWTA is in fact the primary TWTA that was in operation when Landsat 5 launched in 1984, after several issues in late 1986 and 1987, the primary TWTA was turned off and the secondary redundant TWTA was used. The USGS Flight Operations Team applied lessons learned while operating the redundant TWTA to the primary TWTA for its first successful transmission in over 22 years
Death Valley travel guide from Wikivoyage
