Gradup tube dogpile updating
Sunlight is converted to heat at the surface, and to maintain energy balance, this heat must be radiated back to space. The surface will warm to just the temperatrure that is needed, on average, to achieve that outward radiation level. Some parts will be hotter than others, and this will set up local convection cells.Bigger cells will take heat from the tropics to colder parts. So, I hear you say, shouldn't the energy balance include convection from the surface.One thing that doesn't change, though, is that the heat absorbed from the Sun must still get out to space.
As I said, maintaining such a gradient requires a heat pump, because heat tends to move down the gradient by conduction.This is much less than the temperatures we have, and the difference of about 33K is ascribed to the greenhouse effect.