Chihuahuan Desert Rain Shadow Effect

 

Not to over-dwell upon this subject (with this and the two following videos), but the Rain Shadow Effect is the primary "cause" of the four North American Temperate Deserts, the Mojave, the Great Basin, the Sonoran, and the largest, the Chihuahuan Desert.  

The Rain Shadow Effect is the "2nd half" of the Orographic Effect.  The first "half" occurs when prevailing air currents bring moist air masses into contact with linear mountain ranges.  Over the long-term climate effects, due to our Jet Stream position, usually westerly wind currents bring moist air masses in from the Pacific Ocean.  As the moist air is uplifted, it chills, condenses, and brings precipitation to the Windward side of the mountain ranges.

Once the air currents "top" the mountain range(s), as it starts to fall in altitude (down the Leeward side of the mountain ranges), it expands, warms, and dries.  Due to the mountainous areas west of the Rockies Front Range and west of the eastern-most parts of the Basin and Range Province, the Rain Shadow Effect is the primary reason for the prevailing dryness of the "American West".

A secondary "cause" of the four North American Temperate Deserts is the "Mid-Latitude High-Pressure Zone", related to vertical atmospheric cells, called the "Ferrel Cell", in which persistent Atmospheric High-Pressure cells (and associated falling winds) tend to suppress cloud growth.