The heating causes a thermal low to develop which sets up a pressure gradient which induces the wind, pulling cooler air down from the High Sierra.
12.
Thermal lows over the western and southern portions of North America, northern Africa, and southeast Asia are strong enough to lead to summer monsoon conditions.
13.
Because of this extreme heating process, a thermal low is usually noticed near the surface, and is the strongest and the most developed during the summertime.
14.
The monsoon circulation dominates across southern and eastern sections, due to the presence of the Himalayas forcing the formation of a thermal low which draws in moisture during the summer.
15.
This is the case for Siberia were the temperature is very cold in winter forming the Siberian High, or very hot in summer to give a thermal low in summer.
16.
At the same time, the intense heating inland creates a pronounced thermal trough aligned with the Great Central Valley and typically linked to the broader thermal low across the North American deserts.
17.
The North American monsoon is associated with an area of high pressure called the subtropical ridge that moves northward during the summer months and a thermal low ( a trough of low pressure which develops from intense surface heating ) over the Mexican Plateau and the Desert Southwest of the United States.
