This was not something I really expected, but hey, it seems to have some substance. The radiant transfer of energy from a body to another body has two main limits, the energy of the bodies and the background energy of space. I would have thought that background energy would be related to the temperature of space, but it appears to be the energies in the low end of the electromagnetic spectrum.
While there is a lot of work to verify this situation, around 60 Wm-2 of energy flux we hit an unexpected to me thermal barrier. A spectrum with an average energy of 60Wm-2 is in the radio range. Based on the Kelvin temperature scale, a corresponding temperature of about 100K. Neat!
If true, this explains the oddities at the south pole. One being that the measured flux readings appeared to show the signature of the southern magnetic field.
Liquid oxygen has a temperature of around 90K and has magnetic properties. That would be a bit of a verification!
The minimum temperature I have seen for the tropopause with deep convective pluses is -95K lends more support to my Tropopause heat sink theory. See, the tropopause can get no colder than the energy above and below will allow. Stratospheric energy seems to impose this limit, 238Wm-2 divide by 2 is ~120Wm-2 or an equivalent temperature of 214K. This is getting kind of exciting :)