To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

4,5
Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.
.
Leo
Newton
Brights
Milds

Desert climate

From Wikipedia, the free encyclopedia

Regions with desert climates   BWh (hot desert climates)   BWk (cold desert climates)
Regions with desert climates
  BWh (hot desert climates)
  BWk (cold desert climates)

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.[1]

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 mm (0.2 in.). Some locations in the Sahara Desert such as Kufra, Libya record only .86 mm (0.03 inches) of rainfall annually. The official weather station in Death Valley, United States reports only 60 mm (2.3 inches) annually, and in one period between 1931 and 1934 (40 months) only 16 mm (0.64 inches) 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: either a mean annual temperature of 18 °C (which is the most accurate[citation needed] and most commonly used), or a mean temperature of 0 °C or −3 °C 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".

Most desert and arid climates receive between 25 and 200 mm (1 to 8 inches) of rainfall annually.[2] 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 280 for regions that receive 70% or more of their rainfall during the six winter months. The constant is 0 for regions that receive 70% or more of their rainfall during the six summer months. And it is 140 for any climates falling between these two extremes.[3]

YouTube Encyclopedic

  • 1/5
    Views:
    5 379
    72 164
    17 783
    16 163
    3 486
  • ✪ Hot Deserts - Secrets of World Climate, Episode 4
  • ✪ Deserts
  • ✪ Desert Climate Region - World Geography Major Climatic Regions (in Hindi)
  • ✪ C26-Desert Climate - Hot Deserts - Mid latitude Deserts - Formation of Deserts - Minerals in Deserts
  • ✪ Climate of desert

Transcription

Water. Without it life cannot exist. The places on our earth denied it are empty, barren places. And yet even these have a stark, almost unearthly beauty. They are the hottest regions on our planet. They have been the setting for legendary civilisations of the past. And today, against all expectation, they possess large, highly developed cities. Where heat and water are at an extreme imbalance these are the hot and dry deserts of planet Earth. In the first three episodes of this series we’ve been looking at the climates of the Tropics, the central band of the earth around the equator. We now journey out of this zone, heading towards the poles, but first we must pass through the barrier of remarkably aridity, the zone of the hot deserts. Why do these bands of dryness exist? The main reason is to do with the way in which hot and cold air hold onto moisture, and how this is tied into the greater cycle of air movement in the Tropics. In the equatorial region, intense solar radiation leads to heating of warm moist air, which lifts up high into the atmosphere, depositing most of its moisture as rain as it cools. But this air has to go somewhere. In fact, it moves out toward the poles. And it must come down to earth again. And in the places where it does, we get deserts. This is because this air is mostly empty of moisture, but also because it is going from the cool upper atmosphere, to the heat near the ground. Warm air can hold onto more moisture than cold, so any moisture in this descending air remains locked in, and won’t produce rain. These huge and heavy descending columns of air generate high pressure, which causes further heating of the air through compression. In combination with the constant sun, this causes the highest temperatures to be found anywhere on earth, even more than in the tropics. And the high pressure regions keep out storms or other atmospheric disturbances. In short the air is very stable, producing cloudless, sunny skies, very high temperatures, and little to no rain. Most of this air then re-circulates back down to the equator where it forms the Trade Winds that I spoke about in Episode 2. This whole circular airflow is known as a Hadley Cell. It explains how the Tropical Rainforest, Monsoon, Savannah and the deserts are produced, and is one of the great Secrets of World Climate to be revealed. There are other places on earth with little to no rain – what we’d call the cool deserts, such as the Gobi or Atacama. But the mechanism of those is different to described here, and we’ll pick these up in a later episode. In hot and dry climates, there are two main classifications within the Koppen system, distinguished simply by how little rain falls. BWh, the true hot desert, has the least amount of rain, while BSh, known as hot semi-arid, or hot steppe, has some rain, but not enough to produce anything more than stunted, shrub-like vegetation. A third, special category, called BWn, is reserved for special desert areas close to cool oceans where much fog is produced, but still no rain, since the moisture moves in from cool ocean to warmer land and so holds onto its moisture. This fog lowers the temperatures, so these are referred to as mild deserts. There are basically two seasons in these climates, defined principally by temperature, since rain doesn’t feature significantly, or indeed at all. They are a long, very hot summer, and a shorter mild or cool winter. The seasonal variation in temperature depends upon latitude and how far away from the ocean the place is. Places further away from the equator or ocean have greater seasonal variation than those that are closer to one or the other. Compare, for instance the graph of Baghdad to Mogadishu – two desert cities you’ve probably heard of, but for all the wrong reasons. Baghdad is pretty far from the equator – 33 degrees to be precise, and far from any ocean, and has a pretty extreme summer to winter range. While Mogadishu on the Indian Ocean coast of Somalia, and only 2 degrees north of the equator experiences very little seasonal temperature differences. Deserts in general also feature high day/night changes in temperature – this is because the air is dry and so holds little heat when the sun goes down. That, and the lack of cloud cover too, which would otherwise keep heat in. So where in the world do we find significant areas of hot and dry conditions? Starting in the Americas, we have the Mojave desert of the Southwest US, covering inland areas of Southern California, Southern Nevada and much of Arizona. This desert region continues south into north-west Mexico, where it becomes the Sonora desert, plus all of the Baja peninsula. Another desert, the Chihuahuan, covers much of north-east Mexico. In South America, we most notably have the extremely dry coastline of Peru which experiences a great deal of fog due to the cold ocean current that brushes that shoreline. Then there is the Chaco of north-west Argentina. Moving on to Africa, and here we have the largest and most famous desert of all the Sahara. Stretching across the entire northern continent this desert is larger than all the others combined. This enormous region of aridity extends into the Middle East, where it encompasses the entirety of the Arabian Peninsula, south into the Horn of Africa, and further east into southern Iran, Pakistan, ending in the Thar Desert of west India. In Southern Africa, we have the large Namib desert, which also experiences extensive coastal fogs. This desert extends inland where it becomes the Kalahari. Lastly we come to Australia, where the vast majority of that island continent is covered by desert or semi-arid conditions. The so-called “Red Heart” of Australia encompasses many named deserts such as the Great Sandy, Victoria and Gibson. So what kind of landscapes and vegetation do we find in the hot and dry climates? Well, not much, when it comes to vegetation. But this lack, exposes the earth underneath, and is one of the few places where we get to see the rocky “bones” of our planet. In the absence of binding plants and soils, winds pulverise the rock into grains of sand, and these sands can be gathered by those winds into vast dunes. So true deserts are a mix of exposed rock, baked earth and sand dunes. Where there is some rain, the plants that do exist are hardy shrubs that are spaced out with bare earth and rock between. And of course, there are cacti. Uniquely suited to a climate where it might only rain once every few years, these iconic desert plants have evolved to hold onto moisture for years within their tough, fleshy bodies waiting for the next rain. So that’s it for this climate z one. I hope you found it enlightening. If you enjoyed it, please don’t forget to share with others who would find it useful. You can also subscribe to this YouTube channel by clicking the GeoDiode button on screen as well as the Red button below the video. This means you won’t miss future episodes, and also helps me with page rankings so I can grow the Channel. And do leave some comments, particularly if you live or have lived in the hot deserts of our Earth, and how you adapted to it. I want to again thank the many photographers who gave permission for their footage to be shown this video, in particular Milosh Kitchovitch, who also helped with my previous episode. You can check out his channel, and all the others listed via links in the text that accompanies this video. Thanks again for watching, and I’ll see you in the next episode, where I’ll reveal which climate zone has more great world cities than any other. You’ll have to stay tuned to find out which one it is! Until then, stay cool!

Contents

Hot desert climates

Sabha
Climate chart (explanation)
JFMAMJJASOND
 
 
7
 
 
19
6
 
 
0
 
 
21
8
 
 
10
 
 
26
12
 
 
7
 
 
32
17
 
 
1
 
 
36
22
 
 
0
 
 
39
25
 
 
0
 
 
39
25
 
 
0
 
 
39
25
 
 
0
 
 
38
24
 
 
0
 
 
29
19
 
 
1
 
 
26
12
 
 
1
 
 
20
7
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: World Weather Online

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. Hot desert climates 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 (85 to 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, averages which can exceed 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.

Regions with hot desert climates
Regions with hot desert climates

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.[4]

Hot deserts are lands of extremes: most of them are 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.

Cold desert climates

Leh
Climate chart (explanation)
JFMAMJJASOND
 
 
9.5
 
 
−2
−14
 
 
8.1
 
 
2
−11
 
 
11
 
 
7
−6
 
 
9.1
 
 
12
−1
 
 
9
 
 
16
3
 
 
3.5
 
 
22
7
 
 
15
 
 
25
11
 
 
15
 
 
25
10
 
 
9
 
 
22
6
 
 
7.5
 
 
15
−1
 
 
3.6
 
 
8
−7
 
 
4.6
 
 
2
−12
Average max. and min. temperatures in °C
Precipitation totals in mm
Source: [5]
Regions with cold desert climates
Regions with cold desert climates

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 Leh city 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).

See also

References

  1. ^ Peel, M. C.; B. L. Finlayson; T. A. McMahon (2007). "Updated world map of the Köppen-Geiger climate classification" (PDF). Hydrology and Earth System Sciences. 11 (5): 1633–1644. Bibcode:2007HESS...11.1633P. doi:10.5194/hess-11-1633-2007.
  2. ^ Laity, Julie J. (2009). Deserts and Desert Environments. John Wiley & Sons. p. 7. ISBN 978-1444300741.
  3. ^ Peel, M. C.; B. L. Finlayson; T. A. McMahon (2007). "Updated world map of the Köppen-Geiger climate classification" (PDF). Hydrology and Earth System Sciences. 11 (5): 1633–1644. Bibcode:2007HESS...11.1633P. doi:10.5194/hess-11-1633-2007.
  4. ^ "Atlas.pdf" (PDF). Retrieved 2018-09-01.
  5. ^ "Archived copy". Archived from the original on 2018-02-25. Retrieved 2017-08-16.CS1 maint: Archived copy as title (link)

External links

This page was last edited on 9 April 2019, at 09:56
Basis of this page is in Wikipedia. Text is available under the CC BY-SA 3.0 Unported License. Non-text media are available under their specified licenses. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc. WIKI 2 is an independent company and has no affiliation with Wikimedia Foundation.