Ask any climate scientist the question: "Why are deserts so hot in the day time and so cold at night" and generally you will get the same answer, it’s all about the lack of moisture and latent heat and the greenhouse gas effect. Consider however for example, a simple household convection heater that uses the principles of: a radiator, conduction and convection to warm a house. The radiator fins greatly increase the surface area of the heat source to significantly increase the conduction of heat to the air and the basic concept of convection circulated the warm air upward. Very efficient, and control is simply to turn the element on and off with a thermostat. A less used method of control however, but still effective, is simply to block the fins so conduction and convection is reduced.
Enter Mother Nature, with sand deserts covering vast surfaces of the earth. Any geologist will tell you that Aeolian sand deposits can have porosities upwards of over 45%, permeability is unlimited and finally the surface area of the sand grains (on and below the surface) for heat conduction is hundreds of times greater than just a flat non porous surface. The Sahara Desert covers 3.5 million square miles of Aeolian sand deposits. The sun supplies the heat to the sand both at the surface and below (surface conduction grain to grain), the sand grains are the radiator fins that conduct heat to the air and finally convection looks after the rest. Shut off the sun every night and the sand cools very quickly because of the increased conduction and convection soon replaces the hot air with cold.
Most of Europe right now is experiencing a massive heat wave coming from the Sahara Desert to the south and of course blames global warming. The question is "Are Sand Deserts The Greatest Natural Convection Heaters On Earth" and can we control them? We cannot control the sun, but can we not close some of the fins on these "desert convection heaters", perhaps by sealing some of the surfaces of the desert sands with tarps or liquid sealers? Anything that stops the convection will reduce the heat output. Has Mother Nature in the past, been playing with the Earth's thermostat simply by reducing and increasing the size of our great deserts?