Many deserts are found in bands along 30 degrees latitude north and 30 degrees latitude south.(Where those red lines
Some deserts located by mountains and are caused by the "rainshadow" effect. Air moves up over a mountain range, it gets
cold and loses the ability to hold moisture so it rains or snows. When the air moves down the other side of the mountain,
it gets warmer. Warm air can hold lots of moisture, so it doesn't rain as much, and a desert is formed.