Bill Vajk said:
Attributions too complex at this stage AND I was unable
for some reason to reply to Kevin's post. That being
said....
Heat radiates from the earth out into open space with
*no* receiving body involved. Consider heat to be
photons (which it is.) If and when it hits something
it is likely to be absorbed. Otherwise it can travel
forever, just like light or radio waves or x-rays.
increases.
Not true. You can (and do) radiate into a surrounding medium
that's at a higher temperature. BUT the net exchange is larger
incoming than outgoing so it seems as though you're not
radiating at all.
Well, true, but not salient.
"Kelvin" (who should know better, btw, given his handle
is arguing
that its energy that determines the heat of an object. This is true,
until one considers the steady state of the system. Thats what 'Bob'
is arguing, that it's power, which is the time rate of change of
energy, which is important in determining the final temperature T.
My attempted contribution was to show the reason why this is true by
introducing the rate of radiation, the function P(T), which is power
radiated given a particular T above ambient, and asserting that when
P(T) = IIR, the system will be in a steady state. This is the
temperature the system will end up at, given I and R.
I also brought up the notion of thermal resistance, which is the way
one predicts final T given a particular heat sink and power output of
an electronics component. If theta is thermal resistance, and p is
power, then p * theta gives a temperature, which will be the final
temperature at equilibrium.
Walz described in far more detail the physics involved by actually
giving the function P(T).