On Saturday, 8 August 2015 00:25:04 UTC+1,

Alastair,
It is net cooling by radiation you are talking about, as some on this thread have hinted.
You can call it cold radiation if you like, but that is not very scientific despite you finding it at odd places in the literature.

On a clear calm night a land surface cools by radiation.
It loses more heat than it absorbs. Presumably you are calling this cold radiation.
During a sunny day a land surface warms by radiation. Presumably you want to call this warm radiation.

Cold bodies radiate, but your body only feels cold because you are radiating more heat than you are absorbing from the cold body. Net cooling by radiation again.
There is no real need to talk about warm or cold radiation.
In science it is important to understand the energy balance at the surface in question.

I hope this helps.

Len
Wembury

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