Question

why most of the world's deserts are located in western margins of continents in subtropical????

Answer 1

Because of the "Rain Shadow" effect.

Rainshadow deserts are formed because tall mountain ranges prevent moisture-rich clouds from reaching areas on the lee, or protected side, of the range.

As air rises over the mountain, water is precipitated and the air loses its moisture content. A desert is formed in the lee side "shadow" of the range.

When that air reaches the leeward side, it is dry because it has lost the majority of its moisture, resulting in a desert. The air then warms, expands, and blows across the desert. The warm, desiccated air takes with it any remaining moisture in the desert.

Hope this helps.

Answer 2

Answer:

Most of the worlds deserts are located in the western margins of continents in the subtropics because the prevailing winds in the tropics are tropical easterly winds. The tropical easterly winds become dry by the time they reach the western margins of the continents and so they bring no rainfall.