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 are the most common type of climate on earthafter polar climate.
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) annually, but in a 40-month period between 1931 and 1934 a total of 16 mm (0.63 in) of rainfall was measured.
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 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 mean annual temperature of
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 0 for regions that receive 70% or more of their rainfall during the six winter (colder) months, 28 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.
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) in Death Valley, 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.
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 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. The Hautes Plaines is another major example of cold desert climates, located in the northeastern section of Morocco and in Algeria. This is also found in Europe, primarily in Bardenas Reales near Tudela, Navarre, Spain 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).
Climate is the long-term average of weather, typically averaged over a period of 30 years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation. In a broader sense, climate is the state of the components of the climate system, which includes the ocean and ice on Earth. The climate of a location is affected by its latitude, terrain, and altitude, as well as nearby water bodies and their currents.
The Sahara desert, as defined by the World Wide Fund for Nature (WWF), includes the hyper-arid center of the Sahara, between latitudes 18° N 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 increasing north-south temperature differences.
The subtropics are geographic and climate zones located roughly between the tropics at latitude 23.5° and temperate zones north and south of the Equator.
The Köppen climate classification is one of the most widely used climate classification systems. It was first published by the German-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.
An oceanic climate, also known as a marine climate or temperate oceanic climate, is the Köppen classification of climate typical of west coasts in higher middle latitudes of continents, and generally features cool summers and cool but not cold winters, with a relatively narrow annual temperature range and few extremes of temperature. 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. This climate type is often caused by the onshore flow from the cool, high latitude oceans that are found west of their location.
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 four distinct seasons and 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.
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.
California's climate 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 Tabernas Desert is one of Spain's semi-arid deserts, located within Spain's southeastern province of Almería. The 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.
The climate of Mexico is very varied. The Tropic of Cancer effectively divides the country into temperate and tropical zones. Land that is north of the twenty-fourth parallel experiences lower temperatures during the winter months. South of the twenty-fourth parallel, temperatures are fairly consistent all year round and vary solely as a function of elevation. The north of the country usually receives less precipitation than the south.
The Climate of Venezuela is characterized for being tropical and isothermal as a result of its geographical location near the Equator, but because of the topography and the dominant wind direction, several climatic types occur which can be the same as found in temperate latitudes, and even polar regions. Latitude exerts little influence on the Venezuelan climate, but the altitude changes it dramatically, particularly the temperature, reaching values very different according to The weather.
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.
A humid subtropical climate is a zone of climate characterized by hot and humid summers, and cold to mild winters. These climates normally lie on the southeast side of all continents, generally between latitudes 25° and 35° and are located poleward from adjacent tropical climates.
Cyprus has a subtropical climate - Mediterranean and semi-arid type - according to Köppen climate classification signes Csa and BSh, with very mild winters and warm to hot summers. Snow is possible only in the Troodos mountains in the central part of the island. Rain occurs mainly in winter, with summer being generally dry.
The climate in Spain varies across the entire 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:
Due to its vast size and range of altitudes, Argentina possesses a wide variety of climatic regions, ranging from the hot subtropical region in the north to the cold subantarctic in the far south. Lying between those is the Pampas region, featuring a mild and humid climate. Many regions have different, often contrasting, microclimates. In general, Argentina has four main climate types: warm, moderate, arid, and cold in which the relief features, and the latitudinal extent of the country, determine the different varieties within the main climate types.
The Climate of Rajasthan in northwestern India is generally arid or semi-arid and features fairly hot temperatures over the year with extreme temperatures in both summer and winter.
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