Libya occupies a part of northern Africa from 20 to 34° N and 10 to 25° E. It is bounded in the east by Egypt (1,150 km), in the west by Tunisia (459 km), and Algeria (982 km), Mediterranean Sea in the north, and by Sudan (383 km), Chad (1,055 km), and ‘Niger (354 km), in the south (CIA, 2004). It has an important physical asset by its strategic location at the midpoint of Africa’s northern rim. The total area of Libya is about 1.76 Million km2; it ranks fourth in the area among all countries of Africa and 15th among all countries on earth (McMorris, 1979). More than 95% of Libya is desert, which is a part of Sahara, that is the most extensive area of severe aridity. The aridity of the central and eastern Sahara is due to its domination by continental tropical air all-year, which is continually descending from the upper levels of the atmosphere where, in these latitudes, anticyclone conditions are permanent.