This was inspired from a comment by “richardengland”:
“Lets make it really simple: once the hot water has left the kettle can this hot water be made hotter without going back into the kettle and its heating coil? Yes or no.”
And I think that that is actually precisely it, with a slight modification:
Will putting your tea back into the kettle make the kettle hotter than when it poured your tea? That is exactly what they’re claiming when they say that “backradiation” from the atmosphere can heat the warmer surface, the warmer surface from where the thermal energy came from in the first place.
It is exactly the same thing. You can’t put the water back and expect it to make the kettle hotter, and you can’t send the radiation back from where it came to make that place hotter either. Both concepts are obvious, gross, flagrant, childish, and idiotic claims violating the most basic thermodynamics, and childhood empirical exploration.
Why doesn’t “back-tea” heat the kettle further? It emits radiation too after all, from the thermal energy it originally got from the kettle!
I think that this has got to be a new meme: “Back-tea, making your hotter kettle hotter still since never having discovered anything about thermodynamics.”