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.
Deserts. A desert is a hot area of land that gets very little rainânot more than 200 mm a year. Temperatures during the daytime can get as high as 55Â° C. At night, deserts cool down, sometimes even below 0Â° C. Deserts cover about 20% of the worldâs land.ost deserts lie between 15Â° and 35Â° north and south of the equator. They were created by air that rises over the equator and comes down over the Tropic of Cancer and the Tropic of Capricorn. All over the world many deserts lie in these regions. 1  Land over the equator becomes very hot.