The diagram illustrates the step-by-step process through which a rain-shadow desert is formed as moist air passes over a mountain range.
Overall, the formation involves seven sequential stages, including moist winds from the sea that are forced to rise over mountains, where they cool, condense, and produce rainfall on the windward side. By contrast, the leeward side receives little or no precipitation because the descending air is dry, ultimately creating desert conditions inland.
Initially, moist winds blow from the sea towards the coast. When these winds reach the mountains, they are forced to rise along the windward side. As the air rises, it cools down, and clouds begin to form. After that, rain falls on the windward side of the mountain, providing plenty of moisture to this area.
Once the air has released most of its water, it moves over the top of the mountain and continues towards the leeward side. Unlike the air on the windward side, this air is dry because it has already lost its moisture through rainfall. The dry air then travels further inland, where there is very little or no rain. As a result, the inland region becomes extremely dry, leading to the formation of a rain-shadow desert over a large area.