I have been honoured with a drive-by posting from nickreality65 explaining why back radiation does not exist.
Here is his argument;-
RGHE theory could not exist without the concept of “back” radiation, energy/heat moving from a cold tropospheric “surface” to a hot ground “surface.”
Consider a small heated rod of 0.5 m^2 inside a larger outer tube of 2.0 m^2.
The heated rod is fed 25 watts of electricity for a radiative flux of 50 W/m^2.
The outer tube absorbs that radiation for a radiative flux of 12.5 W/m^2.
RGHE theory says that 50 W/m^2 radiate outwards while 12.5 W/m^2 “back” radiates for a net of 37.5 W/m^2 warming the earth.
A watt is not energy, but power, energy over time: 3.412 Btu per English hour or 3.6 kJ per metric hour.
25 watts is 85.3 Btu/h.
25 W spread over area 1 is 50 W/m^2 moving 85.3 Btu/h.
25 W spread over area 2 is 12.5 W/m^2 also moving 85.3 Btu/h.
Conservation of energy demands that input and output must be equal.
The 25 W, 85.3 Btu/h, that entered as electricity must radiate to the world from surface 2, 25 W or 85.3 Btu/h.
There is exactly ZERO left over to “back” radiate.
Without any expectation of a reply, just an exercise in the Socratic method, I asked in response;-
“Is that the total area of the outer tube, inside and out, or just the outer area ?”
I hope it is obvious why this is important.
If nick is defining the OUTER surface of the tube as 2m^2, then the only way it could emit the same outgoing flux as the central rod WITHOUT some back radiation, is if it is perfectly transparent to EM energy. Perhaps made of dark matter ?!
But if the tube is made of some real-world material that interacts with EM energy then there will be some absorption/emission/reflection from the INNER surface of the tube. Back radiation is an inherent and inescapable aspect of any adjacent material objects exchanging energy.
The first of the animations below shows the only circumstances in which there is NO back radiation. When the outer tube is 100% transparent to all outgoing energy. Perhaps it is only detectable by its gravitational effects…
Both cases are physical impossibilities. In even nick’s reality an outer tube will emit energy from both the inner and outer surface. Any back radiation will increase the energy flux within the tube until it is high enough to allow the same amount of energy emitted from the outside of the tube as from the rod in the middle, once equilibrium is reached.
Watch how when the tube reflects 50% of the energy, or it starts to ‘leak’, almost the same amount of energy escapes over a time period, the dots in the outer blue circle, but the energy flux within the tube (grey inner circle) is much higher than in the case of the transparent tube.
For simplicity of illustration the central rod and outer tube are depicted end-on with a square cross-section. In each animation an equal amount of energy quanta are emitted constantly from the central rod. Except in the case of 100% reflection the amount of energy lost to the outer blue circle per unit time is equal to the amount emitted from the central rod, once energy flux increases to compensate for the back radiation within the grey circle.