Hills in the Judean desert. Judea or Judæa ( Hebrew: יהודה Standard Yəhuda Tiberian Yəhûḏāh, "praised

A desert is a landscape or region that receives very little precipitation. Landscape comprises the visible features of an area of land including physical elements such as Landforms living elements of flora and fauna abstract elements such as lighting In Meteorology, precipitation (also known as one class of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric Deserts can be defined as areas that receive an average annual precipitation of less than 250 mm (10 in),^[1][2] or as areas in which more water is lost than falls as precipitation. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to Evapotranspiration (ET is a term used to describe the sum of Evaporation and Plant Transpiration from the earth's land surface to Atmosphere ^[3] In the Köppen climate classification system, deserts are classed as BWh (hot desert) or BWk (temperate desert). The Köppen climate classification is one of the most widely used climate classification systems It was developed by Wladimir Köppen, a German climatologist In the Thornthwaite climate classification system, deserts would be classified as arid megathermal climates. In Climatology, the term megathermal (or less commonly macrothermal) is sometimes used as a synonym for " Tropical. ^[4][5]

Terminology

Deserts are part of a wider classification of regions that, on an average annual basis, have a moisture deficit (i. e. they can potentially lose more than is received). Deserts are located where vegetation cover is exceedingly sparse. ^[6]

Geography

A satellite image of the Sahara, the world's largest hot desert and second largest desert after Antarctica. The Sahara (الصحراء الكبرى aṣ-ṣaḥrā´ al-kubra, "The Great Desert" is the world's largest hot Desert and the world's second largest

Deserts take up one-third of the Earth's land surface. ^[1] They usually have a large diurnal and seasonal temperature range, with high daytime temperatures (in summer up to 45 °C or 113 °F), and low night-time temperatures (in winter down to 0 °C; 32 °F) due to extremely low humidity. Diurnal temperature variation is a Meteorological term that relates to the variation in Temperature that occurs from the highs of the Day to the cool of Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. Water acts to trap infrared radiation from both the sun and the ground, and dry desert air is incapable of blocking sunlight during the day or trapping heat during the night. Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of Sunlight, in the broad sense is the total spectrum of the Electromagnetic radiation given off by the Sun. The term thermal insulation can refer to materials used to reduce the rate of Heat transfer, or the methods and processes used to reduce heat transfer Thus during daylight most of the sun's heat reaches the ground. The Sun (Sol is the Star at the center of the Solar System. As soon as the sun sets, the desert cools quickly by radiating its heat into space. Urban areas in deserts lack large (more than 25 °F/14 °C) daily temperature ranges, partially due to the urban heat island effect. An urban heat island ( UHI) is a metropolitan area which is significantly warmer than its surrounding rural areas

Many deserts are formed by rain shadows, mountains blocking the path of precipitation to the desert. For the Australian television series see Rain Shadow (TV series. Deserts are often composed of sand and rocky surfaces. Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Sand dunes called ergs and stony surfaces called hamada surfaces compose a minority of desert surfaces. In physical Geography, a dune is a Hill of Sand built by Aeolian processes. An erg (also sand sea or dune sea) is a large relatively flat area of Desert covered with Wind -swept Sand with little to no vegetation A hamada ( Arabic, حمادة ḥammāda) is a type of Exposures of rocky terrain are typical, and reflect minimal soil development and sparseness of vegetation. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Vegetation is a general term for the plant life of a region it refers to the Ground cover provided by plants

The snow surface at Dome C Station in Antarctica is a representative of the majority of the continent's surface.

Bottomlands may be salt-covered flats. Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants Eolian processes are major factors in shaping desert landscapes. Aeolian (or Eolian or Æolian) processes pertain to the activity of the Winds and more specifically to the winds' ability to shape the surface of the Cold deserts (also known as polar desert) have similar features but the main form of precipitation is snow rather than rain. Polar deserts are areas with annual precipitation less than 250 Millimetres and a mean Temperature during the warmest month of less than 10° C "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to Antarctica is the world's largest cold desert (composed of about 98 percent thick continental ice sheet and 2 percent barren rock). A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions An ice sheet is a mass of Glacier Ice that covers surrounding terrain and is greater than 50000 km² (20000 mile²) Some of the barren rock is to be found in the so-called Dry Valleys of Antarctica that almost never get snow, which can have ice-encrusted saline lakes that suggest evaporation far greater than the rare snowfall due to the strong katabatic winds that evaporate even ice. "Dry valleys" redirects here For other uses see Dry valley The McMurdo Dry Valleys are a row of Valleys in The salt lake or saline lake is a landlocked body of Water which has a concentration of Salts (mostly Sodium chloride) and other minerals significantly A katabatic wind, from the Greek word katabatikos meaning "going downhill" is the technical name for a drainage Wind, a wind

The largest hot desert is the Sahara. The Sahara (الصحراء الكبرى aṣ-ṣaḥrā´ al-kubra, "The Great Desert" is the world's largest hot Desert and the world's second largest

Deserts sometimes contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Due to extreme and consistent dryness, some deserts are ideal places for natural preservation of artifacts and fossils.

Etymology

English desert and its Romance cognates (including Italian deserto, French désert and Spanish desierto) all come from the Latin desertum, which means "an unpopulated place". Italian ( or lingua italiana) is a Romance language spoken by about 63 million people as a First language, primarily in Italy. This in turn is derived from the Egyptian word dSr. Egyptian is an Afro-Asiatic language most closely related to the Berber, Semitic, Somali and Beja languages t, which literally means "red land" and refers to the desert. The correlation between aridity and sparse population is complex and dynamic, varying by culture, era, and technologies, and thus the use of the word desert can cause confusion. In English prior to the 20th century, desert was often used in the sense of "unpopulated area", without specific reference to aridity; but today the word is most often used in its climate-science sense (an area of low precipitation)—and a desert may be quite heavily populated, with millions of inhabitants. Phrases such as "desert island" and "Great American Desert" in previous centuries did not necessarily imply sand or aridity; their focus was the sparse population. The term desert island, or deserted island, refers to an Island which is uninhabited or sparsely inhabited The Great American Desert is a term that was used in the 19th century to describe the High Plains east of the Rocky Mountains. But the connotation of a hot, parched, sandy place often influences today's popular interpretation of those phrases.

Types of desert

The Thar Desert near Jaisalmer, India

High desert in Eastern Oregon, United States

The Agasthiyamalai hills cut off Tirunelveli (India) from the monsoons, creating a rainshadow region

In 1953, Peveril Meigs divided desert regions on Earth into three categories according to the amount of precipitation they received. The Thar Desert ( Hindi: थार मरुस्थल also known as the Great Indian Desert, is This article is about the city of India For historical region and state see also Jaisalmer state Jaisalmer ( Hindi: जैसालमेर nicknamed India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country Eastern Oregon is the eastern part of the US state of Oregon. The United States of America —commonly referred to as the Agastya Mala (also known as Agastyarkoodam or Agasthyakoodam) is a peak within Neyyar Wildlife Sanctuary in the Western Ghats of South Tirunelveli (திருநெல்வேலி is a city in Tamil Nadu and was formed into a Municipal corporation in 1999 by merging three municipalities viz India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country A monsoon is a seasonal prevailing wind which lasts for several months For the Australian television series see Rain Shadow (TV series. Peveril Meigs III (1903-1979 was an American geographer notable for his studies of arid lands on several continents and in particular for his work on the native peoples and early missions In this now widely accepted system, extremely arid lands have at least 12 consecutive months without rainfall, arid lands have less than 250 millimeters (10 in) of annual rainfall, and semiarid lands have a mean annual precipitation of between 250 and 500 millimeters (10-20 in). Arid and extremely arid lands are deserts, and semiarid grasslands are generally referred to as steppes. In physical Geography, a steppe ( German, from степь - "a flat and arid land" степ - /stɛp/ тал - tal дала - /dɑlɑ/ pronounced ^[1]

Measurement of rainfall alone can't provide an accurate definition of what a desert is because being arid also depends on evaporation which depends in part on temperature. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature For example, Phoenix, Arizona receives less than 250 millimeters (10 in) of precipitation per year, and is immediately recognized as being located in a desert due to its arid adapted plants. Phoenix (ˈfiːˌnɪks O'odham Skikik, Yavapai Wasinka, Western Apache Fiinigis, Navajo Hoozdo, The North Slope of Alaska's Brooks Range also receives less than 250 millimeters (10 in) of precipitation per year, but is not generally recognized as a desert region. The Alaska North Slope is the region of the US state of Alaska located on the northern slope of the Brooks Range along the coast of two marginal seas The Brooks Range is a Mountain range that stretches from west to east across northern Alaska and into Canada 's Yukon Territory, a total distance

So "potential evapotranspiration" supplements measurement of rainfall in providing a scientific measurement-based definition of a desert. Evapotranspiration (ET is a term used to describe the sum of Evaporation and Plant Transpiration from the earth's land surface to Atmosphere The water budget of an area can be calculated using the formula P-PE±S, wherein P is precipitation, PE is potential evapotranspiration rates and S is amount of surface storage of water. Evapotranspiration is the combination of water loss through atmospheric evaporation, coupled with the evaporative loss of water through the life processes of plants. Evaporation is the process by which Molecules in a Liquid state (e Potential evapotranspiration, then, is the amount of water that could evaporate in any given region. As an example, Tucson, Arizona receives about 300 millimeters, (12 in), of rain per year, however about 2500 millimeters, (100 in), of water could evaporate over the course of a year. Tucson (ˈtuːsɒn is the seat of Pima County Arizona, United States, located 118 miles (188 km) southeast In other words, about 8 times more water could evaporate from the region than actually falls. Rates of evapotranspiration in other regions such as Alaska are much lower.

There are different forms of deserts. Cold deserts can be covered in snow or ice; frozen water unavailable to plant life. "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia These are more commonly referred to as tundra if a short season of above-freezing temperatures is experienced, or as an ice cap if the temperature remains below freezing year-round, rendering the land almost completely lifeless. In physical Geography, tundra is an area where the Tree growth is hindered by low temperatures and short growing seasons An ice cap is an Ice mass that covers less than 50 000 km² of land area (usually covering a highland area

Most non-polar deserts are hot in the day and chilly at night (for the latitude) because of the lack of the moderating effect of water. In some parts of the world, deserts are created by a rain shadow effect in which air masses lose much of their moisture as they move over a mountain range; other areas are arid by virtue of being very far from the nearest available sources of moisture. For the Australian television series see Rain Shadow (TV series. A mountain range is a chain of Mountains bordered by highlands or separated from other mountains by passes or valleys

Deserts are also classified by their geographical location and dominant weather pattern as trade wind, mid-latitude, rain shadow, coastal, monsoon, or polar deserts. Polar deserts are areas with annual precipitation less than 250 Millimetres and a mean Temperature during the warmest month of less than 10° C Former desert areas presently in non-arid environments are paleodeserts.

Montane deserts are arid places with a very high altitude; the most prominent example is found north of the Himalaya especially in Ladakh region of Jammu and Kashmir, in parts of the Kunlun Mountains and the Tibetan Plateau. Montane is a biogeographic term which refers to highland areas located below the Subalpine zone Altitude is the Elevation of a point or object from a known level or datum (plural data The Kunlun Mountains ( Mongolian: Хөндлөн Уулс is one of the longest Mountain chains in Asia, extending more than 3000 Km. The Tibetan Plateau, also known as the Qinghai-Tibetan (Qingzang Plateau is a vast elevated Plateau in Central Asia covering most of the Tibet Autonomous Many locations within this category have elevations exceeding 3,000 meters (10,000 ft) and the thermal regime can be hemiboreal. Hemiboreal means halfway between the temperate and subarctic (or Boreal) zones These places owe their profound aridity (the average annual precipitation is often less than 40 mm/1. 5in) to being very far from the nearest available sources of moisture. Montane deserts are normally cold.

Rain shadow deserts form when tall mountain ranges block clouds from reaching areas in the direction the wind is going. For the Australian television series see Rain Shadow (TV series. As the air moves over the mountains, it cools and moisture condenses, causing precipitation on the windward side. In Meteorology, precipitation (also known as one class of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric Moisture almost never reaches the leeward side of the mountain, resulting in a desert. Windward is the direction from which the wind is blowing at the time in question When that air reaches the leeward side, the air is dry, because it has already lost the majority of its moisture. The air then warms, expands, and blows across the desert. The warm, desiccated air takes with it any remaining small amounts of moisture in the desert.

Desert features

Satellite view of Al-Dahna desert in Saudi Arabia showing different depositional features.

Sand covers only about 20 percent of Earth's deserts. Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles Most of the sand is in sand sheets and sand seas—vast regions of undulating dunes resembling ocean waves "frozen" in an instant of time. In general, there are six forms of deserts:

• Mountain and basin deserts
• Hamada deserts, which consist of plateau landforms
• Regs, which consist of rock pavements
• Ergs, which are formed by sand seas
• Intermontane Basins
• Badlands, which are located at the margins of arid lands comprising clay-rich soil

Nearly all desert surfaces are plains where eolian deflation—removal of fine-grained material by the wind—has exposed loose gravels consisting predominantly of pebbles but with occasional cobbles. A hamada ( Arabic, حمادة ḥammāda) is a type of A pebble is a clast of rock with a Particle size of 4 to 64 Millimeters based on the Krumbein phi scale of Sedimentology

The remaining surfaces of arid lands are composed of exposed bedrock outcrops, desert soils, and fluvial deposits including alluvial fans, playas, desert lakes, and oases. Bedrock is the native consolidated rock underlying the surface of a terrestrial planet usually the Earth. Aridisols (or desert soils) are a soil order in USA soil taxonomy. An alluvial fan is a fan -shaped deposit formed where a fast flowing Stream flattens slows and spreads typically at the exit of a Canyon onto A lake (from Latin lacus) is a Terrain feature (or Physical feature) a body of Liquid on the surface of a world that is localized to the Bedrock outcrops commonly occur as small mountains surrounded by extensive erosional plains.

Several different types of dunes exist. Barchan dunes are produced by strong winds blowing across a level surface and are crescent-shaped. Longitudinal or seif dunes are dunes that are parallel to a strong wind that blows in one general direction. Transverse dunes run at a right angle to the constant wind direction. Star dunes are star-shaped and have several ridges that spread out around a point.

Oases are vegetated areas moistened by springs, wells, or by irrigation. In Geography, an oasis (plural oases) or Cienega ( Southwestern United States) is an isolated area of vegetation in a Desert, typically A spring is a point where Groundwater flows out of the ground and is thus where the Aquifer surface meets the ground surface Irrigation is an artificial application of water to the soil usually for assisting in growing crops Many are artificial. Oases are often the only places in deserts that support crops and permanent habitation.

Flora and fauna

Deserts have a reputation for supporting very little life, but in reality deserts often have high biodiversity, including animals that remain hidden during daylight hours to control body temperature or to limit moisture needs. Biodiversity is the variation of Life forms within a given Ecosystem, Biome or for the entire Earth. Some fauna includes the kangaroo rat, coyote, jack rabbit, and many lizards. Kangaroo rats, genus Dipodomys, are small Rodents native to North America. The coyote (kaɪˈoʊti ˈkaɪoʊt ( Canis latrans) also known as the prairie wolf, is a Mammal of the order Carnivora Hares and jackrabbits are Leporids belonging to the Genus Lepus. Lizards are a large and widespread group of Reptiles of the order Squamata, with nearly 5000 species and ranging across all continents except Some flora includes shrubs, Prickly Pears, Desert Holly, and the Brittle bush. Atriplex hymenelytra is a species of saltbush known by the common name desert holly.

Flora of Baja California Desert, Cataviña region, Mexico

Most desert plants are drought- or salt-tolerant, such as xerophytes. Plants are living Organisms belonging to the kingdom Plantae. A xerophyte or xerophytic organism ( xero meaning dry phyte meaning plant is a Plant which is able to survive in an ecosystem with little available Some store water in their leaves, roots, and stems. Other desert plants have long taproots that penetrate to the water table if present, or have adapted to the weather by having wide-spreading roots to absorb water from a greater area of the ground. A Plant 's taproot is a straight tapering Root that grows vertically down ROOT is an object-oriented program and library developed by CERN. Area is a Quantity expressing the two- Dimensional size of a defined part of a Surface, typically a region bounded by a closed Curve. Another adaptation is the development of small, spiny leaves which shed less moisture than deciduous leaves with greater surface areas. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. Botany Autumn leaf color. See --> In Botany and Horticulture, deciduous Plants, including The stems and leaves of some plants lower the surface velocity of sand-carrying winds and protect the ground from erosion. Even small fungi and microscopic plant organisms found on the soil surface (so-called cryptobiotic soil) can be a vital link in preventing erosion and providing support for other living organisms. In more Arid regions vegetative cover is generally sparse Open spaces are usually covered by a biological soil crust or biocrust, a highly specialized community

Saguaros in the Sonoran Desert of Arizona

Deserts typically have a plant cover that is sparse but enormously diverse. The Saguaro, pronounced "sah-wah-roh" ( Carnegiea gigantea) is a large tree-sized Cactus Species in the Monotypic genus The Sonoran Desert (sometimes called the Gila Desert after the Gila River or the Low Desert in opposition to the higher Mojave Desert) is The State of Arizona ( is a state located in the southwestern region of the United States. The giant saguaro cacti of the Sonoran Desert provide nests for desert birds and serve as "trees" of the desert. The Saguaro, pronounced "sah-wah-roh" ( Carnegiea gigantea) is a large tree-sized Cactus Species in the Monotypic genus The Sonoran Desert (sometimes called the Gila Desert after the Gila River or the Low Desert in opposition to the higher Mojave Desert) is Saguaro grow slowly but may live up to 200 years. When 9 years old, they are about 15 centimeters (6 in) high. After about 75 years, the cacti develop their first branches. When fully grown, saguaro cacti are 15 meters tall and weigh as much as 10 tons. They dot the Sonoran and reinforce the general impression of deserts as cactus-rich land.

Although cacti are often thought of as characteristic desert plants, other types of plants have adapted well to the arid environment. A cactus (plural cacti) is any member of the Spine plant family Cactaceae, native to the Americas They include the pea and sunflower families. A pea (inaccurately called a '''sweet pea''' by food distubutors is most commonly the small spherical Seed or the seed-pod of the Legume Pisum The sunflower ( Helianthus annuus) is an Annual plant in the family Asteraceae and native to the Americas, with a large flowering Cold deserts have grasses and shrubs as dominant vegetation.

Water

The shifting sands simulator at Questacon, Canberra

Rain does fall occasionally in deserts, and desert storms are often violent. Questacon – the National Science and Technology Centre, is located on the southern shore of Lake Burley Griffin in Canberra, Australia. A record 44 millimeters (1. 7 in) of rain once fell within 3 hours in the Sahara. Large Saharan storms may deliver up to 1 millimeter per minute. Normally dry stream channels, called arroyos or wadis, can quickly fill after heavy rains, and flash floods make these channels dangerous. An arroyo (literally brook in Spanish) also called a wash or draw, is a usually dry creek bed or Gulch that temporarily Wadi (وادي) (also Vadi) is traditionally a valley In some cases it can refer to a dry riverbed that contains water only during times of heavy rain A flash flood is a rapid flooding of geomorphic lowlying areas - washes rivers and streams

Though little rain falls in deserts, deserts receive runoff from ephemeral, or short-lived, streams fed considerable quantities of sediment for a day or two. Although most deserts are in basins with closed or interior drainage, a few deserts are crossed by 'exotic' rivers that derive their water from outside the desert. Such rivers infiltrate soils and evaporate large amounts of water on their journeys through the deserts, but their volumes are such that they maintain their continuity. The Nile River, the Colorado River, and the Yellow River are exotic rivers that flow through deserts to deliver their sediments to the sea. The Nile (النيل, Ancient Egyptian iteru or Ḥ'pī, Coptic piaro or phiaro) is a major north-flowing River The Colorado River (' Aha Kwahwat in Mojave) is a River in the southwestern United States and northwestern Mexico, approximately The Yellow River or Huang He / Hwang Ho ( Hatan Gol Queen river) is the second-longest river in China (after the Yangtze River) and the Deserts may also have underground springs, rivers, or reservoirs that lie close to the surface, or deep underground. Plants that have not completely adapted to sporadic rainfalls in a desert environment may tap into underground water sources that do not exceed the reach of their root systems.

Lakes form where rainfall or meltwater in interior drainage basins is sufficient. Desert lakes are generally shallow, temporary, and salty. Because these lakes are shallow and have a low bottom gradient, wind stress may cause the lake waters to move over many square kilometers. When small lakes dry up, they leave a salt crust or hardpan. In Soil science, Agriculture and Gardening, hardpan is a general term for a dense layer of Soil, residing usually below the uppermost The flat area of clay, silt, or sand encrusted with salt that forms is known as a playa. There are more than a hundred playas in North American deserts. Most are relics of large lakes that existed during the last ice age about 12,000 years ago. An ice age is a period of long-term reduction in the Temperature of the Earth 's surface and atmosphere resulting in an expansion of continental Ice sheets Lake Bonneville was a 52,000 kilometers² (20,000 mi²) lake almost 300 meters (1000 ft) deep in Utah, Nevada, and Idaho during the Ice Age. Lake Bonneville was a prehistoric Pluvial lake that covered much of North America 's Great Basin region Today the remnants of Lake Bonneville include Utah's Great Salt Lake, Utah Lake, and Sevier Lake. Great Salt Lake, located in the northern part of the US state of Utah, is the largest salt lake in the western hemisphere the fourth-largest terminal Utah Lake, at, is the largest natural Freshwater Lake in the state of Utah and a remnant of the Prehistoric Lake Bonneville, which Sevier Lake (sɛˈviːr is an intermittent and Endorheic lake which lies in the lowest part of the Sevier Desert, Millard County Utah. Because playas are arid landforms from a wetter past, they contain useful clues to climatic change.

When the occasional precipitation does occur, it erodes the desert rocks quickly and powerfully.

The flat terrains of hardpans and playas make them excellent racetracks and natural runways for airplanes and spacecraft. Ground-vehicle speed records are commonly established on Bonneville Speedway, a racetrack on the Great Salt Lake hardpan. Bonneville Speedway is an area of the Bonneville Salt Flats near Wendover Utah, that is marked out for Space shuttles land on Rogers Lake Playa at Edwards Air Force Base in California. Edwards Air Force Base is a United States Air Force base located on the border of Kern County and Los Angeles County California in the Antelope

Mineral resources

Some mineral deposits are formed, improved, or preserved by geologic processes that occur in arid lands as a consequence of climate. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Ground water leaches ore minerals and redeposits them in zones near the water table. Groundwater is Water located beneath the Ground surface in Soil pore spaces and in the Fractures of lithologic formations An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining The water table is the level at which the ground water pressure is equal to Atmospheric pressure. This leaching process concentrates these minerals as ore that can be mined.

Evaporation in arid lands enriches mineral accumulation in their lakes. Lake beds known as Playas may be sources of mineral deposits formed by evaporation. Water evaporating in closed basins precipitates minerals such as gypsum, salts (including sodium nitrate and sodium chloride), and borates. Gypsum is a very soft Mineral composed of Calcium sulfate dihydrate with the Chemical formula Ca[[sulfur S]] O 4·2 Sodium nitrate is the Chemical compound with the formula NaNO3 For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Borates in Chemistry are Chemical compounds containing Boron bonded to three Oxygen atoms written as B(OR3 The minerals formed in these evaporite deposits depend on the composition and temperature of the saline waters at the time of deposition. Evaporites (iˈvæpəraɪt are water-soluble Mineral sediments that result from the Evaporation of bodies of surficial Water.

Significant evaporite resources occur in the Great Basin Desert of the United States, mineral deposits made famous by the "20-mule teams" that once hauled borax-laden wagons from Death Valley to the railroad. The Great Basin is a large arid region of the western United States. Death Valley is the lowest driest and hottest Valley in the United States. Boron, from borax and borate evaporites, is an essential ingredient in the manufacture of glass, enamel, agricultural chemicals, water softeners, and pharmaceuticals. Boron (ˈbɔərɒn is a Chemical element with Atomic number 5 and the chemical symbol B. Borax (from Persian burah) also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important Boron Borates are mined from evaporite deposits at Searles Lake, California, and other desert locations. Searles Lake (also called Searles Dry Lake) is an evaporite basin located near the community of Trona in San Bernardino County, California. The total value of chemicals that have been produced from Searles Lake substantially exceeds US$1 billion. The United States dollar ( sign: $; code: USD) is the unit of Currency of the United States; it has also been

The Atacama Desert of Chile is unique among the deserts of the world in its great abundance of saline minerals. Atacama redirects here for the political-administrative region of Chile, see Atacama Region. Chile, officially the Republic of Chile ( Spanish:) is a country in South America occupying a long and narrow Coastal strip wedged between the Sodium nitrate has been mined for explosives and fertilizer in the Atacama since the middle of the 19th century. An explosive material is a material that either is chemically or otherwise Energetically unstable or produces a sudden expansion of the material usually accompanied Fertilizers ( also spelt fertiliser are chemical compounds given to Plants to promote growth they are usually applied either through the soil for uptake by plant Nearly 3 million tonnes were mined during World War I. This article is about the tonne or metric ton For other tons see Ton. World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All

Valuable minerals located in arid lands include copper in the United States, Chile, Peru, and Iran; iron and lead-zinc ore in Australia; chromite in Turkey; and gold, silver, and uranium deposits in Australia and the United States. Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Peru (Perú Piruw Piruw officially the Republic of Peru ( reˈpuβlika del peˈɾu is a country in western South America. For a topic outline on this subject see List of basic Iran topics. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 For a topic outline on this subject see List of basic Australia topics. Chromite is iron magnesium chromium oxide (Fe MgCr2O4 It is an Oxide Mineral belonging to the Spinel group Turkey (Türkiye known officially as the Republic of Turkey ( is a Eurasian Country that stretches Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Nonmetallic mineral resources and rocks such as beryllium, mica, lithium, clays, pumice, and scoria also occur in arid regions. Beryllium (bəˈrɪliəm is a Chemical element with the symbol Be and Atomic number 4 The word "mica" is thought to be derived from the Latin word la micare, "glitteren" in reference to the brilliant appearance of this mineral (especially Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and Pumice is a textural term for a volcanic rock that is a solidified frothy lava composed of highly microvesicular glass Pyroclastic with very thin translucent Scoria is a textural term for macrovesicular Volcanic rock. It is commonly but not exclusively Basaltic or andesitic in composition Sodium carbonate, sulfate, borate, nitrate, lithium, bromine, iodine, calcium, and strontium compounds come from sediments and near-surface brines formed by evaporation of inland bodies of water, often during geologically recent times. Sodium carbonate (also known as washing soda or soda ash), is a Sodium Salt of Carbonic acid. In Inorganic chemistry, a nitrate is a salt of Nitric acid with an Ion composed of one Nitrogen and three Oxygen atoms Iodine (ˈaɪədaɪn ˈaɪədɪn or /ˈaɪədiːn/ from ιώδης iodes "violet" is a Chemical element that has the symbol I and Atomic Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Strontium (ˈstrɒntiəm /ˈstrɒnʃiəm/) is a Chemical element with the symbol Sr and the Atomic number 38

The Green River Formation of Colorado, Wyoming, and Utah contains alluvial fan deposits and playa evaporites created in a huge lake whose level fluctuated for millions of years. The Green River Formation is an Eocene geologic formation that records the sedimentation in a series of intermountain lakes The State of Colorado ( or chiefly by nonresidents) is a state located in the Rocky Mountain region of the United States of America. The State of Wyoming ( is a sparsely populated state in the western region of the United States. The State of Utah (ˈjuːtɔː or) is a western state of the United States. Alluvium (from the Latin, alluvius, from alluere, "to wash against" is Soil or Sediments deposited by a river or other running Economically significant deposits of trona, a major source of sodium compounds, and thick layers of oil shale were created in the arid environment. This page is about the mineral For the town please see Trona California; for the geological feature please see Trona Pinnacles. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22

Some of the more productive petroleum areas on Earth are found in arid and semiarid regions of Africa and the Mideast, although the oil fields were originally formed in shallow marine environments. Petroleum ( L petroleum, from Greek πετρέλαιον, lit An oil field is a region with an abundance of Oil wells extracting Petroleum (crude oil from below ground Recent climate change has placed these reservoirs in an arid environment. It's noteworthy that Ghawar, the world's largest and most productive oilfield is mostly under the Empty Quarter and Al-Dahna deserts. Ghawar (Arabicالغوار is an Oil field in Saudi Arabia. It is located about 100 km WSW from the city of Dhahran in Al-Ahsa county The Rub' al Khali ( Arabic: الربع الخالي which translates as Empty Quarter in English, is one of the largest sand Deserts in the

Other oil reservoirs, however, are presumed to be eolian in origin and are presently found in humid environments. The Rotliegendes, a hydrocarbon reservoir in the North Sea, is associated with extensive evaporite deposits. In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. The North Sea is a marginal, Epeiric sea of the Atlantic Ocean on the European Continental shelf. Many of the major U. S. hydrocarbon resources may come from eolian sands. Ancient alluvial fan sequences may also be hydrocarbon reservoirs.

Human life in deserts

Mahktesh Gadol, an erosional basin in the Negev Desert of southern Israel. The Negev (נֶגֶב Tiberian vocalization: Néḡeḇ) is the Desert region of southern Israel.

A desert is a hostile, potentially deadly environment for unprepared humans. In hot deserts, high temperatures cause rapid loss of water due to sweating, and the absence of water sources with which to replenish it can result in dehydration and death within a few days. Dehydration ( hypohydration) is the removal of Water ( hydro in ancient Greek) from an object In addition, unprotected humans are also at risk from heatstroke. Hyperthermia, in its advanced state referred to as heat stroke or sunstroke, is an acute condition which occurs when the Body produces or absorbs more

Humans may also have to adapt to sandstorms in some deserts, not just in their adverse effects on respiratory systems and eyes, but also in their potentially harmful effects on equipment such as filters, vehicles and communication equipment. In living organisms a respiratory system functions to allow Gas exchange. An air filter is a device which removes solid Particulates such as Dust, Pollen, Mold, and bacteria from Air. Sandstorms can last for hours, sometimes even days.

Despite this, some cultures have made hot deserts their home for thousands of years, including the Bedouin, Tuareg tribe and Pueblo people. The Bedouin, (from the Arabic (ar بدوي pl badū) are a desert-dwelling Arab Nomadic pastoralist, or previously The Tuareg (also Twareg or Touareg, Amazigh: Imuhagh / Itargiyen, besides regional ethnyms are a Nomadic The Pueblo people are a Native American people in the Southwestern United States. Modern technology, including advanced irrigation systems, desalinization and air conditioning have made deserts much more hospitable. Irrigation is an artificial application of water to the soil usually for assisting in growing crops Desalination, desalinization, or desalinisation refers to any of several processes that remove excess salt and other Minerals from Water The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort. In the United States and Israel for example, desert farming has found extensive use. The United States of America —commonly referred to as the For a topic outline on this subject see List of basic Israel topics. Desert farming generally relies on Irrigation, as it is the easiest way to make a Desert bloom

In cold deserts, hypothermia and frostbite are the chief hazards, as well as dehydration in the absence of a source of heat to melt ice for drinking. Hypothermia is a condition in which an organism's temperature drops below that required for normal Metabolism and bodily functions Frostbite ( congelatio in Medical terminology) is the Medical condition whereby damage is caused to Skin and other tissues Dehydration ( hypohydration) is the removal of Water ( hydro in ancient Greek) from an object Falling through pack-ice or surface ice layers into freezing water is a particular danger requiring emergency action to prevent rapid hypothermia. Starvation is also a hazard; in low temperatures the body requires much more food energy to maintain body heat and to move. Food energy is the amount of Energy in food that is available through Digestion. As with hot deserts, some people such as the Inuit have adapted to the harsh conditions of cold deserts. Inuit (plural the singular Inuk, means "man" or "person" is a general term for a group of culturally similar Indigenous peoples inhabiting

Most traditional human life in deserts is nomadic. Nomadic people, (from the νομάδες nomádes, "those who let pasture herds" also known as nomads, are communities of people that It depends in hot deserts on finding water, and on following infrequent rains to obtain grazing for livestock. In cold deserts, it depends on finding good hunting and fishing grounds, on sheltering from blizzards and winter extremes, and on storing enough food for winter. Permanent settlement in both kinds of deserts requires permanent water and food sources and adequate shelter, or the technology and energy sources to provide it.

Many deserts are flat and featureless, lacking landmarks, or composed of repeating landforms such as sand dunes or the jumbled ice-fields of glaciers. Advanced skills or devices are required to navigate through such landscapes and inexperienced travellers may perish when supplies run out after becoming lost. In addition sandstorms or blizzards may cause disorientation in severely-reduced visibility. A blizzard is a severe Winter storm condition characterized by low Temperatures strong Winds and heavy blowing Snow Blizzards are formed when

The danger represented by wild animals in deserts has featured in explorers' accounts but does not cause higher rates of death than in other environments such as rainforests or savanna woodland, and generally does not by itself affect human distribution. Defence against polar bears may be advisable in some areas of the Arctic, as may precautions against venomous snakes and scorpions in choosing sites at which to camp in some hot deserts. The polar bear ( Ursus maritimus) is a Bear native to the Arctic Ocean and its surrounding seas A venomous snake is a Snake that uses modified saliva venom, usually delivered through highly specialized teeth such as hollow fangs for the purpose of Prey Scorpions are eight-legged Carnivorous Arthropods They are members of the order Scorpiones within the class Arachnida. Definition Camping describes a range of activities Survivalist campers set off with little more than their boots whereas Recreational vehicle travelers arrive equipped

Examples of desert climate

Southern hemisphere

See also

• Desertification
• International Center for Agricultural Research in the Dry Areas
• List of deserts
• List of deserts by area (size)
• List of North American deserts
• Aridification

References

External links

• The Desert Biome. University of California Museum of Paleontology (1996). The University of California ( UC) is a Public university system in the state of California.

• Global Deserts Outlook. United Nations Environment Programme (UNEP) (2006). The UN Environment Programme (or UNEP) coordinates United Nations environmental activities assisting developing countries in implementing environmentally sound policies , a report in the Global Environment Outlook (GEO) series. The UNEP Global Environment Outlook (GEO project was initiated in response to the environmental reporting requirements of Agenda 21 and to a UNEP Governing Council
• Map with biodiversity scenarios for desert areas, from the Global Deserts Outlook.