The desert climate (in the Köppen climate classification BWh and BWk), is a climate in which there is an excess of evaporation over precipitation. The typically bald, rocky, or sandy surfaces in desert climates hold little moisture and evaporate the little rainfall they receive. Covering 14.2% of earth's land area, hot deserts may be the most common type of climate on earth.
The Köppen climate classification is one of the most widely used climate classification systems. It was first published by the Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notably in 1918 and 1936. Later, the climatologist Rudolf Geiger introduced some changes to the classification system, which is thus sometimes called the Köppen–Geiger climate classification system.
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. The surrounding gas must not be saturated with the evaporating substance. When the molecules of the liquid collide, they transfer energy to each other based on how they collide with each other. When a molecule near the surface absorbs enough energy to overcome the vapor pressure, it will escape and enter the surrounding air as a gas. When evaporation occurs, the energy removed from the vaporized liquid will reduce the temperature of the liquid, resulting in evaporative cooling.
In meteorology, precipitation is any product of the condensation of atmospheric water vapour that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, snow, graupel and hail. 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 water vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. 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."
Although no part of Earth is known for certain to be absolutely rainless, in the Atacama Desert in northern Chile, the average annual rainfall over a period of 17 years was only 5 millimetres (0.20 in). Some locations in the Sahara Desert such as Kufra, Libya record only 0.86 mm (0.034 in) of rainfall annually. The official weather station in Death Valley, United States reports 60 mm (2.4 in), but in a 40-month period between 1931 and 1934 a total of 16 mm (0.63 in) of rainfall was measured.
The Atacama Desert is a desert plateau in South America covering a 1000-km (600-mi) strip of land on the Pacific coast, west of the Andes mountains. The Atacama desert is one of the driest places in the world, as well as the only true desert to receive less precipitation than the polar deserts. According to estimates, the Atacama Desert occupies 105,000 km2 (41,000 sq mi), or 128,000 km2 (49,000 sq mi) if the barren lower slopes of the Andes are included. Most of the desert is composed of stony terrain, salt lakes (salares), sand, and felsic lava that flows towards the Andes.
Kufra is a basin and oasis group in the Kufra District of southeastern Cyrenaica in Libya. At the end of nineteenth century Kufra became the center and holy place of the Senussi order. It also played a minor role in the Western Desert Campaign of World War II.
Libya is a country in the Maghreb region in North Africa, bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad to the south, Niger to the southwest, Algeria to the west, and Tunisia to the northwest. The sovereign state is made of three historical regions: Tripolitania, Fezzan and Cyrenaica. With an area of almost 1.8 million square kilometres (700,000 sq mi), Libya is the fourth largest country in Africa, and is the 16th largest country in the world. Libya has the 10th-largest proven oil reserves of any country in the world. The largest city and capital, Tripoli, is located in western Libya and contains over one million of Libya's six million people. The second-largest city is Benghazi, which is located in eastern Libya.
There are two variations of a desert climate: a hot desert climate (BWh), and a cold desert climate (BWk). To delineate "hot desert climates" from "cold desert climates", there are three widely used isotherms: most commonly[ citation needed ] a mean annual temperature of 18 °C (64.4 °F), or sometimes a mean temperature of 0 or −3 °C (32.0 or 26.6 °F) in the coldest month, so that a location with a BW type climate with the appropriate temperature above whichever isotherm is being used is classified as "hot arid" (BWh), and a location with the appropriate temperature below the given isotherm is classified as "cold arid" (BWk).
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation. About one-third of the land surface of the world is arid or semi-arid. This includes much of the polar regions where little precipitation occurs and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location.
Most desert and arid climates receive between 25 and 200 mm (1 and 8 in) of rainfall annually. In the Köppen classification system, a climate will be classed as arid if its mean annual precipitation in millimeters is less than ten times its defined precipitation threshold, and it will be classed as a desert if its mean annual precipitation is less than five times this threshold. The precipitation threshold is twice its mean annual temperature in degrees Celsius, plus a constant to represent the distribution of its rainfall throughout the year. This constant is 28 for regions that receive 70% or more of their rainfall during the six winter (colder) months, 0 for regions that receive such a share of rainfall during the six summer months, and 14 for those in-between.
|Climate chart (explanation)|
Hot desert climates (BWh) are typically found under the subtropical ridge in the lower middle latitudes, often between 20° and 33° north and south latitude. In these locations, stable descending air and high pressure aloft create hot, arid, conditions with intense sunshine. Hot desert climates are generally hot, sunny and dry year-round. They are found across vast areas of North Africa, the Middle East, northwestern parts of the Indian Subcontinent, interior Australia, and smaller areas of the Southwestern United States, and Chile. This makes hot deserts present in every continent except Europe and Antarctica.
North Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Morocco in the west, to Egypt's Suez Canal and the Red Sea in the east. Others have limited it to the countries of Algeria, Morocco, and Tunisia, a region that was known by the French during colonial times as "Afrique du Nord" and is known by Arabs as the Maghreb. The most commonly accepted definition includes Algeria, Sudan, Morocco, Tunisia, Libya and Egypt, the 6 countries that shape the top North of the African continent. Meanwhile, "North Africa", particularly when used in the term North Africa and the Middle East, often refers only to the countries of the Maghreb and Libya. Egypt, being also part of the Middle East, is often considered separately, due to being both North African and Middle Eastern at the same time.
The Middle East is a transcontinental region centered on Western Asia, Turkey, and Egypt. Saudi Arabia is geographically the largest Middle Eastern nation while Bahrain is the smallest. The corresponding adjective is Middle Eastern and the derived noun is Middle Easterner. The term has come into wider usage as a replacement of the term Near East beginning in the early 20th century.
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It is the largest country in Oceania and the world's sixth-largest country by total area. The neighbouring countries are Papua New Guinea, Indonesia and East Timor to the north; the Solomon Islands and Vanuatu to the north-east; and New Zealand to the south-east. The population of 25 million is highly urbanised and heavily concentrated on the eastern seaboard. Australia's capital is Canberra, and its largest city is Sydney. The country's other major metropolitan areas are Melbourne, Brisbane, Perth and Adelaide.
At the time of high sun (summer), scorching, desiccating heat prevails. Hot-month average temperatures are normally between 29 and 35 °C (84 and 95 °F), and midday readings of 43–46 °C (109–115 °F) are common. The world absolute heat records, over 50 °C (122 °F), are generally in the hot deserts, where the heat potential is the highest on the planet. This includes the record of 56.7 °C (134.1 °F), which is currently considered the highest temperature recorded on Earth. 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, exceeding 30 °C (86 °F). This last feature is seen in sections of Africa and Arabia. During colder periods of the year, night-time temperatures can drop to freezing or below due to the exceptional radiation loss under the clear skies. However, very rarely do temperatures drop far below freezing.
The highest temperature recorded on Earth has been measured in three different major ways: air, ground, and through satellite. The former of the three is used as the standard measurement, and is noted by the World Meteorological Organization among others for the official record. How the record is taken though has been subject to controversy regarding various factors such as environmental conditions. For ninety years a former record that was measured in Libya had been in place until it was disproven in 2012. This finding has since raised questions about the legitimacy of the current record which was measured in Death Valley. The WMO has since stated that they would be willing to open an investigation into the matter as all "available evidence" points to its accuracy. While there have been higher reports through air readings, none of these have ever been verified. The other two measurements of ground and satellite have also generated higher readings, but are less reliable and also unverified.
Africa is the world's second largest and second most-populous continent, being behind Asia in both categories. At about 30.3 million km2 including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, the Isthmus of Suez and the Red Sea to the northeast, the Indian Ocean to the southeast and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagos. It contains 54 fully recognised sovereign states (countries), nine territories and two de facto independent states with limited or no recognition. The majority of the continent and its countries are in the Northern Hemisphere, with a substantial portion and number of countries in the Southern Hemisphere.
Hot desert climates can be found in the deserts of North Africa such as the wide Sahara Desert, the Libyan Desert or the Nubian Desert; deserts of the Horn of Africa such as the Danakil Desert or the Grand Bara Desert; deserts of Southern Africa such as the Namib Desert or the Kalahari Desert; deserts of the Middle East such as the Arabian Desert, the Syrian Desert or the Lut Desert; deserts of South Asia such as Dasht-e Kavir, Dasht-e Loot, or the Thar Desert of India and Pakistan; deserts of the United States and Mexico such as the Mojave Desert, the Sonoran Desert or the Chihuahuan Desert; deserts of Australia such as the Simpson Desert or the Great Victoria Desert and many other regions.
Hot deserts are lands of extremes: most of them are among the hottest, the driest and the sunniest places on Earth because of nearly constant high pressure; the nearly permanent removal of low pressure systems, dynamic fronts and atmospheric disturbances; sinking air motion; dry atmosphere near the surface and aloft; the exacerbated exposure to the sun where solar angles are always high.
|Climate chart (explanation)|
Cold desert climates (BWk) usually feature hot (or warm in a few instances), dry summers, though summers are not typically as hot as hot desert climates. Unlike hot desert climates, cold desert climates tend to feature cold, dry winters. Snow tends to be rare in regions with this climate. The Gobi Desert in Mongolia is a classic example for cold deserts. Though hot in the summer, it shares the very cold winters of the rest of Central Asia. Cold desert climates are typically found at higher altitudes than hot desert climates and are usually drier than hot desert climates.
Cold desert climates are typically located in temperate zones, usually in the rain shadow of high mountains, which restrict precipitation from the westerly winds. An 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 Kyzyl Kum, Taklamakan and Katpana Desert deserts of Central Asia and the drier portions of the Great Basin Desert of the western United States are other major examples of BWk climates. The Ladakh region, and the city of Leh in the Great Himalayas in India, also has a cold desert climate. This is also found in Europe, primarily in Bardenas Reales near Tudela, Navarre and high altitude parts of the Tabernas Desert in Almería, Spain.
Arctic and Antarctic regions also receive very little precipitation during the year, owing to the exceptionally cold dry air; however, both of them are generally classified as having polar climates because they have average summer temperatures below 10 °C (50 °F).
The Sahara Desert ecoregion, as defined by the World Wide Fund for Nature (WWF), includes the hyper-arid center of the Sahara, between 18° and 30° N. It is one of several desert and xeric shrubland ecoregions that cover the northern portion of the African continent.
A Mediterranean climate or dry summer climate is characterized by dry summers and mild, wet winters. The climate receives its name from the Mediterranean Basin, where this climate type is most common. Mediterranean climate zones are typically located along the western sides of continents, between roughly 30 and 45 degrees north and south of the equator. The main cause of Mediterranean, or dry summer climate, is the subtropical ridge which extends northwards during the summer and migrates south during the winter due to greater temperature differences.
An oceanic climate, also known as a marine climate or maritime climate, is the Köppen classification of climate typical of west coasts in higher middle latitudes of continents, and generally features mild summers and mild winters, with a relatively narrow annual temperature range and few extremes of temperature, with the exception for transitional areas to continental, subarctic and highland climates. Oceanic climates are defined as having a monthly mean temperature below 22 °C (72 °F) in the warmest month, and above 0 °C (32 °F) in the coldest month.
A semi-arid climate or steppe climate is the climate of a region that receives precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of semi-arid climates, depending on variables such as temperature, and they give rise to different biomes.
A humid continental climate is a climatic region defined by Russo-German climatologist Wladimir Köppen in 1900, typified by large seasonal temperature differences, with warm to hot summers and cold winters. Precipitation is usually distributed throughout the year. The definition of this climate regarding temperature is as follows: the mean temperature of the coldest month must be below −3 °C (26.6 °F) and there must be at least four months whose mean temperatures are at or above 10 °C (50 °F). In addition, the location in question must not be semi-arid or arid. The Dfb, Dwb and Dsb subtypes are also known as hemiboreal.
India has a large variation in climate from region to region, due to its vast size. India experiences climate from four major climate groups. These can be further subdivided into seven climatic types. For ecological regions, see Ecoregions of India, for Regions see List of regions of India.
An aridity index (AI) is a numerical indicator of the degree of dryness of the climate at a given location. A number of aridity indices have been proposed ; these indicators serve to identify, locate or delimit regions that suffer from a deficit of available water, a condition that can severely affect the effective use of the land for such activities as agriculture or stock-farming.
The climate of Peru is very diverse, with a large variety of climates and microclimates, including 28 of the 32 world climates. Such a diversity is chiefly conditioned by the presence of the Andes mountains and the cold Humboldt Current
The climate of California varies widely, from hot desert to polar, depending on latitude, elevation, and proximity to the coast. California's coastal regions, the Sierra Nevada foothills, and much of the Central Valley have a Mediterranean climate, with warmer, drier weather in summer and cooler, wetter weather in winter. The influence of the ocean generally moderates temperature extremes, creating warmer winters and substantially cooler summers in coastal areas.
The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by Leslie Holdridge in 1947, and updated in 1967. It is a relatively simple system based on few empirical data, giving objective mapping criteria. A basic assumption of the system is that both soil and climax vegetation can be mapped once the climate is known.
The Tabernas Desert is one of Spain's semi-arid deserts, located within Spain's southeastern province of Almería. The Tabernas desert is located in the interior, about 30 kilometers (19 mi) north of the provincial capital, Almería, in the Tabernas municipality. Due to its high altitude and inland location, it has slightly higher annual rainfall and lower annual average temperature than coastal areas of Almeria. It is a nature reserve spanning 280 square kilometres.
Tropical savanna climate or tropical wet and dry climate is a type of climate that corresponds to the Köppen climate classification categories "Aw" and "As". Tropical savanna climates have monthly mean temperatures above 18 °C (64 °F) in every month of the year and typically a pronounced dry season, with the driest month having less than 60 mm of precipitation and also less than 4% of total annual precipitation.
The climate of Mexico is highly varied. The Tropic of Cancer effectively divides the country into temperate and tropical zones. Land north of the twenty-fourth parallel experiences lower temperatures during the winter months. South of the twenty-fourth parallel, temperatures are fairly constant year round and vary solely as a function of elevation. The north of the country generally receives less precipitation than the south.
A humid subtropical climate is a zone of climate characterized by hot and humid summers, and cool to mild winters. These climates normally lie on the southeast side of all continents, generally between latitudes 25° and 40° and are located poleward from adjacent tropical climates. While many subtropical climates tend to be located at or near coastal locations, in some cases they extend inland, most notably in China and the United States, where they exhibit more pronounced seasonal variations and sharper contrasts between summer and winter, as part of a gradient between the more tropical climates of the southern coasts of these countries and the more continental climates of China and the United States’ northern and central regions.
Earth rainfall climatology Is the study of rainfall, a sub-field of Meteorology. Formally, a wider study includes water falling as ice crystals, i.e. hail, sleet, snow. The aim of rainfall climatology is to measure, understand and predict rain distribution across different regions of planet Earth, a factor of air pressure, humidity, topography, cloud type and raindrop size, via direct measurement and remote sensing data acquisition. Current technologies accurately predict rainfall 3–4 days in advance using numerical weather prediction. Geostationary orbiting satellites gather IR and visual wavelength data to measure realtime localised rainfall by estimating cloud albedo, water content, and the corresponding probability of rain. Geographic distribution of rain is largely governed by climate type, topography and habitat humidity. 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 monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes. The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming may also cause changes in the precipitation pattern globally, including wetter conditions at high latitudes and in some wet tropical areas, and drier conditions in parts of the subtropics and middle latitudes. Precipitation is a major component of the water cycle, and is responsible for depositing most of the fresh water on the planet. Approximately 505,000 cubic kilometres (121,000 cu mi) of water falls as precipitation each year; 398,000 cubic kilometres (95,000 cu mi) of it over the oceans. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes.
The climate in Spain varies across the country. Spain is the most climatically diverse country in Europe with 13 different Köppen climates, excluding the Canary Islands, and is within the 10 most climatically diverse countries in the world. Five main climatic zones can be distinguished, according to Guzman geographical situation and orographic conditions:
Wonominta, New South Wales is a remote rural locality and civil parish of Evelyn County in far northwest New South Wales. located at 30°18′40″S 141°05′05″E.
The Parish of Wygah, New South Wales located at 30°00′35″S 141°37′52″ is a remote rural locality and civil parish of Evelyn County, New South Wales in far northwest New South Wales.
Parish of Kooltoo, New South Wales is a remote civil parish of Yantara County in far North West New South Wales. The geography of the parish is mostly the flat, arid landscape of the Channel Country. The parish has a Köppen climate classification of BWh.
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