What makes a desert is not necessarily heat, but lack of rainfall. Most of the equatorial regions are rather wet, due to being bordered by an awful lot of acerage of various oceans. One thing being warm over water does is evaporate it up into clouds, ready to rain back down on everything else.
Persistent weather patterns have much more to do with where deserts are than how “hot” they are. Where prevailing winds don’t blow clouds and weather systems, or where natural barriers prevent the clouds from being blown there, is where you find deserts.
There is a desert of sorts west of the Cascades in the northwestern US because the Cascades block the weather systems from reaching there (this is also why it’s always wet in Seattle – that’s where the rain is forced to land). There’s the Atacama desert in Chile because the Andes block the weather systems from reaching there. The Gobi desert (notably, a cold desert) is there because the Himalayas block all the weather systems from reaching there… etc.
The Sahara exists because it is massively landlocked, so it’s hard for moisture from the ocean to reach most of it, and also because it sits precisely in the horse latitudes. That’s an area on the globe where there are no trade winds and thus no prevailing airstream to bring rain and weather systems into the area. There are two major stripes of horse latitudes, one each in the northern and southern hemispheres. The Sahara sits in the northern one, as does part of the Gobi and the American great plains. And perhaps unsurprisingly, much of Austrailia sits in the other one.
What makes a desert is not necessarily heat, but lack of rainfall. Most of the equatorial regions are rather wet, due to being bordered by an awful lot of acerage of various oceans. One thing being warm over water does is evaporate it up into clouds, ready to rain back down on everything else.
Persistent weather patterns have much more to do with where deserts are than how “hot” they are. Where prevailing winds don’t blow clouds and weather systems, or where natural barriers prevent the clouds from being blown there, is where you find deserts.
There is a desert of sorts west of the Cascades in the northwestern US because the Cascades block the weather systems from reaching there (this is also why it’s always wet in Seattle – that’s where the rain is forced to land). There’s the Atacama desert in Chile because the Andes block the weather systems from reaching there. The Gobi desert (notably, a cold desert) is there because the Himalayas block all the weather systems from reaching there… etc.
The Sahara exists because it is massively landlocked, so it’s hard for moisture from the ocean to reach most of it, and also because it sits precisely in the horse latitudes. That’s an area on the globe where there are no trade winds and thus no prevailing airstream to bring rain and weather systems into the area. There are two major stripes of horse latitudes, one each in the northern and southern hemispheres. The Sahara sits in the northern one, as does part of the Gobi and the American great plains. And perhaps unsurprisingly, much of Austrailia sits in the other one.