Why most of the world desert are located in western margin of continent subtropic?
Answers
Have already answered this question. That question although was specific to hot deserts and specified latitudinal extent too, but answer will remain same for your question too. Here it is:-
Hot Deserts of the World
Arabian Desert in Arabian peninsula
Great Sandy, Victoria, Simpson, Gibson and Sturt deserts in Australia
Chihuahuan Desert in north central Mexico
Kalahari Desert in south-western Africa
Mojave Desert in USA
Monte Desert in Argentina
Sahara Desert in North Africa
Sonoran Desert in North and Central America
Thar Desert in India and Pakistan
There are four major reasons responsible for why the major hot deserts of the world are located between 20°-30° N on the west of the continents:-
Offshore trade winds in the region and location in rain shadow zone:- Trade winds that blow in the region, shed their moisture on the eastern part and by the time they reach the western margin, they become dry.
Anticyclonic conditions:- Areas between 20–30 degree latitudes on western margins of continents are the regions of descending air. It means the air gets compressed and warm as it descends and thus the moisture keeps decreasing.
Leeward sides of mountains/parallel mountain ranges:- In the case of few deserts, mountains are situated as a barrier which prevents orographic rainfall. For example:- presence of Rockies on the western coast of North America does not let moisture bearing winds do rainfall in leeward sides. In the case of Thar desert in India, Aravallis are situated parallel to the region. Therefore the moisture holding winds pass away from the region because there is absence of mountain barriers.
Presence of cold ocean currents along the western coast of continents tend to stabilise the air over the coast. This prevents cloud formation and rainfall.
You can see it here in the map that major deserts are located on the western parts of continents between 30 degrees North and South latitudes.
Most of the deserts of the world are located in the western margin because of the following reasons:
1. Offshore trade winds travel from eastern to western region and so it rains in the eastern region but when it finally reaches the western region it is absolutely dry.
2. Anti-cyclonic conditions prevailing in the area which leads to the air getting warm and compressed, thereby reducing the moisture content.
3.Presence of mountains in that area( leeward side) prevents the moisture containing winds from generating rainfall.
4.Cold ocean currents which are found along the western coast prevent rainfall.