1. What is a DESERT ?

12. Total Rainfall 2.5 mm Wadi Halfa, Sudan(21 o N, 31 o E ) Rainfall mm Temp o C

13. An area with dry climate, sometimes defined as having a total annual rainfall of less than 250 250 mm Dry regions with very little vegetation

15. Characteristics of deserts: 1. Absence / sparse vegetation 2. Very low and variable rainfall 3. Low humidity 4. High evaporation rate 5. Clear Skies 6. Large daily range of temperature

16. Clear sky with little or no cloud cover enables maximum insolation input Air temperature 40 - 50 o C Absence of vegetation cover

17. Maximum outgoing outgoing radiation radiation Clear sky with no cloud cover Air temperature 5 - 10 o C