If during a warm day we look either at the shadow of any object cast on a bank, or over a level plain at a distant landmark, the effect of an ascending current
of heated air is almost always evident: such upward currents, it has been remarked, are also shown by the ascent of soap-bubbles, which will not rise in an in-doors room.
The ascending current
feeds volcanoes across that broad region, revealing itself with a distinct chemical signature, according to the scientists.
Hot mantle rock starts to rise and gradually forms a huge ascending current
under the middle of the land mass.
The exterior surface of the photosphere being the limit that will attain the ascending currents which carry the phenomenon of incandescence in the superior layers, a very-admissible symmetry suffices in a globe where the most complete homogeneity must have freely established itself, to give to this limit surface the shape of a sphere, but a sphere that is incredibly uneven.
As for the faculae, there is nothing simpler assuredly that such level differences at the extreme limit of our ascending currents, and nothing so difficult to understand for those who admit the liquid photosphere.
One leading theory is that ascending currents
within the Great Red Spot dredge up material from deep down, and that trace compounds containing sulfur, phosphorus, and hydrocarbons turn red when exposed to solar ultraviolet radiation.