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.
The four major North American deserts of this type are the Chihuahuan, Sonoran, Mojave and Great Basin. Others outside the U.S. include the Southern Asian realm, Neotropical (South and Central America), Ethiopian (Africa) and Australian. The seasons are generally warm throughout the year and very hot in the summer.
The deserts in this list range from some of the hottest to some of the coldest places on. The world's 10 biggest deserts are found on just about every continent, many of them forming in the shadow of immense mountain ranges that block moisture from nearby oceans or bodies of water. They're often the site of unusual rock formations and, in some cases, amazing archaeological finds. Elizabeth Howell is a regular contributor to Live Science and Space.com, along with several other science publications. She is one of a handful of Canadian reporters who specializes in space reporting.