Why is the Sahara desert an example of an extreme environment?

The Sahara desert is hot because this hot desert is located in the subtropical regions called the horse latitudes. The hot deserts located in subtropical latitudes are formed by the atmospheric circulation, more precisely the Hadley Cell, characterized by a dry descending, sinking air towards the ground. When the air descends, it warms up considerably and forms a hot weather year-round. This subtropical zone of sinking air is called the subtropical ridge.