Introduction:
- Northern Africa across tropic of Cancer
- 6km2 across 10 countries
Characteristics:
- Climate: Air circulation causing little moisture over tropics & high pressure of descending air
- Rainfall: Less than 100mm annual rainfall – mainly via thunderstorms after long periods of drought
- Fluvial processes are intermittent but powerful
- Temperature: More than 30oC annual temperature average,
- Over 50oC in summer, 0oC freezing in winter, huge diurnal variations
- High variation causes thermal fracture and freeze-thaw weathering
- Winds: Prevailing winds from NE carry large amounts of dust
- Chergui wind carries wind from S to N in Tunisia- hot & dry wind coming from Sahara Desert
- Soil: Dry, little organic matter causing saline landforms
- Sediment is very mobile due to erosion so can easily be transported and used for processes
- Vegetation: Sparse with low diversity- Concentrations along wadis & depressions after rainfall – plants grow rapidly creating a temporary cover
Desert Landforms:
| Name | Process | Example |
| Deflation Hollows | Deflation- Aeolian | Qattara Depression in Egypt is the biggest in world at 18100km2 and 133m below sea level at lowest point. Could have been started from a past stream valley and deepened by deflation and salt weathering
|
| Wadis | Erosion
Fluvial |
Wadi Howar is 1100km long, created from the old Yellow Nile from 9500 to 4500 years ago and runs through Chad and Sudan |
| Yardangs | Erosion
Aeolian |
Yardans in the Aorounga Impact crater in Chad are formed from northeasterly prevailing winds |
| Dunes | Deposition
Aeolian |
The Great Sand Sea covers a 72000km2 area across Libya and Egypt. 2/3 are seif dunes running north to south from prevailing winds |