Quaternary climates Is our climate changing? First, it is important here to note the differences between weather and climate.
A geographical map of Africa, showing the ecological break that defines the Saharan area An oasis in the Ahaggar Mountains. Oases support some life forms in extremely arid deserts. It is one of three distinct physiographic provinces of the African massive physiographic division. The highest peak in the Sahara is Emi Koussia shield volcano in the Tibesti range of northern Chad.
The central Sahara is hyperaridwith sparse vegetation. The northern and southern reaches of the desert, along with the highlands, have areas of sparse grassland and desert shrubwith trees and taller shrubs in wadiswhere moisture collects.
In the central, hyperarid region, there are many subdivisions of the great desert: These extremely arid areas often receive no rain for years. To the north, the Sahara skirts the Mediterranean Sea in Egypt and portions of Libya, but in Cyrenaica and the Maghrebthe Sahara borders the Mediterranean forest, woodland, and scrub eco-regions of northern Africa, all of which have a Mediterranean climate characterized by hot summers and cool and rainy winters.
According to the botanical criteria of Frank White  and geographer Robert Capot-Rey,   the northern limit of the Sahara corresponds to the northern limit of date palm cultivation and the southern limit of the range of espartoa grass typical of the Mediterranean climate portion of the Maghreb and Iberia.
The southern limit of the Sahara is indicated botanically by the southern limit of Cornulaca monacantha a drought-tolerant member of the Chenopodiaceaeor northern limit of Cenchrus biflorusa Geography climate change essay typical of the Sahel.
Climate The Sahara is the world's largest low-latitude hot desert. The area is located in the horse latitudes under the subtropical ridgea significant belt of semi-permanent subtropical warm-core high pressure where the air from upper levels of the troposphere tends to sink towards the ground.
This steady descending airflow causes a warming and a drying effect in the upper troposphere. The sinking air prevents evaporating water from rising and, therefore, prevents the adiabatic cooling, which makes cloud formation extremely difficult to nearly impossible. The stability of the atmosphere above the desert prevents any convective overturning, thus making rainfall virtually non-existent.
As a consequence, the weather tends to be sunny, dry and stable with a minimal risk of rainfall.
Subsiding, diverging, dry air masses associated with subtropical high-pressure systems are extremely unfavorable for the development of convectional showers. The lowering of air is the strongest and the most effective over the eastern part of the Great Desert, in the Libyan Desert which is the sunniest, driest and the most nearly "rain-less" place on the planet rivaling the Atacama Desertlying in Chile and Peru.
The rainfall inhibition and the dissipation of cloud cover are most accentuated over the eastern section of the Sahara rather than the western. The prevailing air mass lying above the Sahara is the continental tropical cT air mass, which is hot and dry.
Hot, dry air masses primarily form over the North-African desert from the heating of the vast continental land area, and it affects the whole desert during most of the year. Because of this extreme heating process, a thermal low is usually noticed near the surface, and is the strongest and the most developed during the summertime.
The Sahara High represents the eastern continental extension of the Azores High ,[ citation needed ] centered over the North Atlantic Ocean. The subsidence of the Sahara High nearly reaches the ground during the coolest part of the year while it is confined to the upper troposphere during the hottest periods.
The effects of local surface low pressure are extremely limited because upper-level subsidence still continues to block any form of air ascent. Also, to be protected against rain-bearing weather systems by the atmospheric circulation itself, the desert is made even drier by his geographical configuration and location.
Indeed, the extreme aridity of the Sahara can not be only explained by the subtropical high pressure. The Atlas Mountainsfound in Algeria, Morocco and Tunisia also help to enhance the aridity of the northern part of the desert.
These major mountain ranges act as a barrier causing a strong rain shadow effect on the leeward side by dropping much of the humidity brought by atmospheric disturbances along the polar front which affects the surrounding Mediterranean climates. The primary source of rain in the Sahara is the Intertropical Convergence Zonea continuous belt of low-pressure systems near the equator which bring the brief, short and irregular rainy season to the Sahel and southern Sahara.
Rainfall in this giant desert has to overcome the physical and atmospheric barriers that normally prevent the production of precipitation. The harsh climate of the Sahara is characterized by: The highest values are very close to the theoretical maximum value.
The Sahara has a huge potential for solar energy production. Sahara desert The constantly high position of the sun, the extremely low relative humidity, and the lack of vegetation and rainfall make the Great Desert the hottest continuously large area worldwide, and the hottest place on Earth during summer in some spots.
Salah, well known in Algeria for its extreme heat, has average high temperatures of There are even hotter spots in the Sahara, but they are located in extremely remote areas, especially in the Azalailying in northern Mali. Some examples of this are: BilmaNiger and Faya-Largeau, Chad. Sand and ground temperatures are even more extreme.
However, it is a myth that the nights are cold after extremely hot days in the Sahara.Has sudden climate change occurred before? Yes. About 55 million years ago, at the end of the Paleocene, there was a sudden warming event in which temperatures rose by about 6˚C globally and by ˚C at the poles .
Climate Change in Residence: Future Scenarios. In December , Culture and Climate Change launched the Scenarios project in Paris during COP Physical Geography is a sub-discipline of two much larger fields of study - Geography and Earth Sciences.
The main purpose of Physical Geography is to explain the spatial characteristics of the various natural phenomena associated with the Earth's .
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Preface. India planned to build six fast breeder reactors in (down to two in ), despite the high cost, instability, danger, and accidents of the 16 attempts that shut down, including the Monju fast breeder in Japan, which began decommissioning in