The Science Behind Desert Dryness.
Deserts are dry due to global air circulation patterns, with the Hadley cell driving trade winds and influencing the location of many of the world's biggest deserts. Wind patterns and topography also play a role, with inland areas being drier due to the lack of moisture in the air. Climate change is expected to expand the zone that's ripe for desert formation, and human activity such as deforestation is contributing to the growth of existing deserts.