Question

Major hot deserts in northern hemisphere are located between 20-30 degree north and on the western side of the continents. Why?

Answer 1

Answer:

Explanation: because:-

Offshore trade winds

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 holding capacity 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

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

Answer 2

Explanation:

There are four main reasons that are responsible for all the major hot deserts of the world to be situated between 20 to 30 degrees North and on the western side of continents. (1) Offshore trade winds and location in a rain shadow zone. The trade winds that blow in a region lose their moisture on the eastern part. By the time they reach the western side, they become dry and without any water in them. (2) Anticyclonic conditions. The areas between 20 to 30 degree North latitudes on the western margins of continents are the regions where air generally comes down. The air gets compressed and warm over here as it descends. Hence, the moisture holding capacity goes low. (3) Parallel mountain ranges or the Leeward sides of mountains. In the case of certain deserts, the mountains are located as a barrier. This prevents orographic rainfall. For example, the presence of Rockies on the western coast of North -America does not allow moisture laden winds to have a rain on its leeward side. In the case of Thar desert in India, the Aravalli Hills are parallel to the region. So, the moisture laden winds pass off from the region as there is an absence of mountain barriers. (4) The presence of cold ocean currents along the western coast of continents help to stabilise the air over its coast. This also stops the formation of cloud and rainfall.