Desert
Hot deserts are mostly in the subtropics. They can be covered by sand, rock, salt lakes, stony hills and even mountains. Most non-polar deserts are hot in the day and chilly at night. The temperature in the daytime can reach  or higher in the summer, and dip to  or lower at night time in the winter. The largest hot desert in the world is the Sahara in North Africa. It is almost as large as Europe or the United States.