Given what we know about the mechanisms surrounding weather, we can confirm that Large deserts receive less rainfall due to the lack of bodies of water and "rainshadows".
Rainshadow is a term used to describe the effects of nearby mountains on the rainfall amounts of a desert. The mountain causes the air to rise greatly and lose moisture. This moisture is received by the mountain, which means that it does not reach the desert area.
Another limiting factor for the amount of rainfall received by deserts is the lack of bodies of water in the area. Once a desert is formed, it tends to lack large bodies of water. This limits the rainfall it receives given that there is no water nearby to evaporate and cause the formation of clouds.
