Why most of the wworld's deserts are located in the western margins of continents in the subtrophics
Most of the deserts are located in the western margin of continents in subtropics due to the fact that the winds are easterly. Therefore, the eastern margins receive more precipitation and moisture. The western margins are comparatively dry and thus deserts are concentrated in these regions. The trade winds also blow towards equator at west coasts and drive surface water offshore. This results in upwelling of cold water at west coasts and causes drier climate at western margin of continents.