The Thermodynamics of Tagines

Tagines work like closed nuclear cooling towers. The purpose of the hyperboloid cover is to cool the evaporating liquid and recycle it back slowly into the cooking pot thus allowing it to cook at a low temperature in the barest of liquid.

This also has the advantage of having the meat, vegetables or fish cook in their own broth. The broth is extracted from the underlying ingredients, turned into steam which condenses and drops back down. You get an intensely brothy liquid since the entire system is "sealed" for all practical purposes.

The heat supply from the flame is kept intentionally low. This is basically a very efficient braise with the heat coming from below rather than all around. It's very heat efficient compared to a traditional braise since you are not wasting time heating an oven where air is actually a very poor conductor of heat. Important for a culture where fuel was traditionally a very large expense.

Ancient science figured out empirically but actually quite amazing!