What is a Watt???

[Derek]

Hi All,
A quick post holiday "update".

A W/m2 is a power figure, or if you prefer a "pressure" figure,
it is a temperature signal.

Years ago an Uncle of mine whilst explaining electricity to me, used a water pipe simile.
He said, imagine pipes carrying water rather than electricity.
Volts is the pressure, and amps is the pipe diameter.
You can not work much out about the flow of water or electricity without knowing the pressure (voltage) and the diameter of the pipe (amps).
This all makes sense to me as a simple analogy to "visualise" electricity flows.

W/m2 is a pressure figure, therefore it assumes the objects being compared are the same size / mass, etc, if they are not,
then another figure for "diameter" is needed.
How can so many have missed "diameter" of the pipes involved is missing from K&T and "greenhouse" ???????

"Greenhouse" is taught as,
1) Solar input received at earth's surface = 239W/m2.
2) 239 W/m2 is radiated by the earth's surface.
3) The atmosphere is heated up to the same temperature and thus radiates up and down 239W./m2.
So, the earth radiates from the atmosphere 239 W/m2 as it should to space, ie, earth appears to be -18C when viewed from space, as it should be,
AND,
the earth's surface is 239W/m2 from the sun, AND 239W/m2 from the atmosphere, 478W/m2 = +15C*.

So, "greenhouse" is taught as "pressure" only, but, if one includes amount of energy, or "diameter",
then earth's surface only receives 1 (directly from the sun) at 239 W/m2 + 1/2 ("back radiated" from the atmosphere) at 239 W/m2,
which is too little for earth's surface, according to "GH" to be 15C.
AND,
Earth should only radiate half the amount of energy it receives, at 239 W/m2 from the sun to space...
According to "GH" "theory".

* = 15C is a very questionable and often quoted supposed "Global Mean Temperature" (GMT),
That IS NOT the earth's surface temperature.
The 15C as quoted so frequently, is infact a near surface air temperature, as measured (usually at about 6 foot above the actual surface), and statistically produced by dubious methods.
Which is a different thing completely to earth's actual surface temperature.
The actual surface temperature, or any attempt at a meaningful global mean of it,
is infact completely absent from such descriptions.