- A cooler object near a warmer object will slow the rate of cooling of the warmer object because of the exchange of energy to and fro between the two objects before that energy departs the combined system.
- If there is a constant energy input throughout then the slowing down of the rate of cooling will cause the warmer object to settle at a higher equilibrium temperature than would otherwise have been the case.
- Thus the presence of the cooler object does indeed result in the warmer object becoming warmer than it otherwise would have done.
- That is the essence of the greenhouse effect which is a concept I have always accepted despite the misleading nomenclature.
- Any sceptical viewpoints that rely on denying those simple facts must be rejected because they weaken the sceptical cause.
måndag 26 juli 2010
Necessity of High Pitch Screaming to Get Heard
In previous posts on the myth of of backradiation we have discovered that a cold blackbody B can get heated by absorbing radiation from a warmer blackbody A. We have seen that B can "read" the spectrum of the incoming radiation and thereby "understand" that it has a lower temperature than A, without literally measuring the temperature of A, thus allowing to get heated by A because A "is stronger".
But how does A get to "know" that B has a lower temperature? Is it necessary?
Let us compare with making yourself heard over a the background noise of a party after a couple of drinks: You read the pitch of the background noise and modulate your screaming pitch so that it gets across. The body A thus can read the pitch of the background noise, that is the temperature of B, and thus understand what level/pitch of screaming will be necessary.
We understand that the cold B reads the coherent high frequency fine detail spectrum of A and converts it to incoherent heat, while A only has to read the overall spectrum of B or its cut-off level, to set up its effective emission.
In other words, the emission of A is relative to the background given by the colder B.
But B does not warm A in some form of two-way heating with backradiation.
Similarly, a blogger has to overpower a certain level of background noise, if you want to get listened to. The temperature/pitch of the blog must be bigger than that of the background.
Notice that it is the pitch that counts, not the amplitude: A small hot blogger (or Sun at distance) can heat a big lukewarm blogosphere (or big Earth), but not the other way around.
A high pitch soprano can get heard over a big orchestra. A melody on top can be heard over
a powerful bass line.
Insulation works by establishing (a sequence of) relative temperature/pitch differences which add up to a total temperature difference. This is the way a cloud layer helps to keep the Earth surface warm during night. Not by backradiation!
Computational Blackbody Radiation gives the math.
This is (more or less) correct, but has nothing to do with backradiation and to call it a "greenhouse effect" is severely misleading. As misleading as saying that an insulating blanket on your bed warms because of a mystical "greenhouse effect" based on mystical "backradiation". In science you are not allowed to deliberately use misleading terminology, only in politics, and maybe not even there in the long run...
PS "Slowing of cooling" is a bit misleading because the cooling is not slowed; it is the temperature which is "lifted" to a higher relative level.