3. Free electives: Free electives are courses in addition to the Core Curriculum and major requirements sufficient to reach a minimum of 120 credit hours for graduation. Students may graduate with more but not less than 120 credit hours.
Evaporation rates regularly exceed rainfall rates. Sometimes rain starts falling and evaporates before reaching the ground. Rainfall is lowest on the Atacama Desert of Chile, where it averages less than 1.5 cm. Some years are even rainless. Inland Sahara also receives less than 1.5 cm a year. Rainfall in American deserts is higher  almost 28 cm a year.
One of the most famous deserts in the world is the Sahara (meaning 'greatest desert' in Arabic) and it is in fact the biggest classical desert in the world, apart from the above mentioned Antarctic and Arctic deserts.There is also a difference in types of deserts.he Sonoran desert is one of the largest and hottest deserts in the Americas and it covers the southeast of California and the southwest of Arizona in the US, and the northhwest Mexican states of Sonora, Baja California, and Baja California Sur. To the north of this 'low desert' is the 'high desert' Mojave.