Extensive deserts occur in the western tropical regions of continents because

Extensive deserts occur in the western tropical regions of continents because of the effect of both the offshore easterly trade winds & cold ocean currents. Trade minds blow away from the western sides of the continents thus dumping the moisture they carry from oceans on eastern sides of other continents. Also, there are cold ocean currents on western side near almost all continents due to which scanty or no rain occurs in the sea water.