By being hotter than the surface. It's not as if that never happens.
Of course your problem talking with JC is that he has chosen to go with SSDD's nonsense but without SSDD's awareness (such as it is) the idea of the atmosphere slowing the radiant heat loss of the surface by sending a portion of it back at the surface is just a bit too complicated for him to grasp.
Of course your problem talking with JC is that he has chosen to go with SSDD's nonsense but without SSDD's awareness (such as it is) the idea of the atmosphere slowing the radiant heat loss of the surface by sending a portion of it back at the surface is just a bit too complicated for him to grasp.