In this part I rebut English/Irish
physicist John Tyndall's claim to an atmospheric greenhouse effect.
In 1861 Tyndall presented a
quantification of the EMR absorption of various gases in a lecture to the Royal
Society of London [1].
Depicted in Fig 1
is a rig he worked on for several weeks.
Figure 1: Tyndall's Experiment
Substance
|
Galvanometer deflection
angle (degrees)
|
Air
|
Fraction of a degree
|
Oxygen
|
Fraction of a degree
|
Nitrogen
|
Fraction of a degree
|
Hydrogen
|
Fraction of a degree
|
Carbonic
oxide (CO)
|
18
|
Carbonic
acid (CO2)
|
25
|
Nitrous
oxide
|
44
|
Olefiant
gas (ethene)
|
61
|
Table
1: Gas's relative absorptive power
He found that gases such as
carbon dioxide and ethene (similar to methane) absorbed more infrared than
gases such as oxygen and nitrogen. But
this state is only made possible because the gas under examination is kept
cooler than the heat source.
The gas only absorbs light from
the heat source, or absorbs and re-emits less than the heat source, because its temperature is kept lower than the heat source via a
liquid cooling system.
While EMR is exchanged
two ways between heat source and gas target, in an energy sense heat only
flows one way "down the energy hill" from warmer to cooler. This heat is then removed mechanically by the
water cooling system. The atmosphere has nothing like
this cooling system and so Tyndall's experiment is useless as a model for it.
Key:
| G |
|
gas source |
| Y, R, Z |
|
gas purifying tubes |
| C |
|
Leslie Cube heat
sources |
| H |
|
heat screen |
| P |
|
thermocouple pile |
| N |
|
measuring galvanometer |
| S' S |
|
gas tube target |
| A |
|
hand cranked vacuum pump |
| F |
|
evacuated, water cooled chamber |
| V |
|
water cooling system |
Figure 2: Breakdown of the
Tyndall experiment. Note particularly
the gas target tube is water cooled -- like today's water cooled CPUs -- and
therefore has no bearing on earth's actual atmosphere. The experiment therefore does not prove the
existence of an atmospheric greenhouse effect.
Absorption of infrared in the tube means that the
galvanometer will deflect. But had the gas
chamber been allowed to warm to the same temperature as the heat source, the measuring
galvanometer would not deflect at all because the tube would emit IR at roughly the
same rate as the heat source (disregarding emissivity). In other
words, the absorption and subsequent galvanometer deflection is
only made possible because of the water cooling system.
Thermally, the atmosphere is
considered to be one entity with no heat sources or sinks aside from its
contact with earth's surface, sunlight and the latter's subsequent re-radiation
back into outer space.
By conventional theory the top
layers of the atmosphere are considered to be cooler than the bottom layers not because there is
a heat sink in upper layers but because gravitational energy is exchanged for
heat energy with increasing altitude.
Figure 3: Decreasing temperature with height.
Any energy trapped by carbon
dioxide would accumulate and result in a hotspot like this:
But a hotspot is not to be found (as
discussed elsewhere like
here or
here).
Only the warmer ground below can
heat the cooler air above with EMR, because the ground is warmer than the
air. This heat flow is one way:
specifically out. The EMR trapped in
earth's atmosphere can't be recycled to do work again, and it does no extra
work when it comes back down as "backradiation".
Carbon dioxide absorbs EMR and
converts it to heat in the atmosphere at the same rate that heat in the
atmosphere is imparted to it and is emitted as EMR; and as the process is equal
and reciprocal there is no net energy gain.
Tyndall performed the opposite experiment, of heating rather than cooling the gases, and found that gases that were good absorbers were equally good emitters.
Substance
|
|
Galvanometer deflection
angle (degrees)
|
|
|
|
Air
|
|
0
|
Oxygen
|
|
0
|
Nitrogen
|
|
0
|
Hydrogen
|
|
0
|
Carbonic
oxide
|
|
12
|
Carbonic
acid
|
|
18
|
Nitrous
oxide
|
|
29
|
Olefiant
gas
|
|
53
|
Table
2: The emitting power of gases mimics the absorptive power [1].
That's why a substance's absorption lines coincide with their emission lines -- it all depends on the relative temperatures involved.
Figure 5: emission/absorption lines.
Despite Tyndall's lecture coming
after publications concerning Kirchhoff's law of thermal radiation in 1860, and
despite his own experience -- that good infrared absorbers are equally good emitters -- he failed to recognise how this could apply to the atmosphere's
energy content as a whole.
A few decades earlier, French
mathematician Joseph Fourier claimed an atmospheric greenhouse effect could
exist by increasing the atmosphere's density [3].
Tyndall tried to build on this theory by
saying that only a change in composition of the atmosphere is required to
change the temperature, and therefore the climate, of the earth.
Earth is supposed to be,
according to conventional calculations, 33C warmer than it "should" be. If something is at a higher temperature than
before, then the increase in temperature is also an increase in energy. Yet it remains to be explained by conventional authorities just how greenhouse gases can develop such extra
energy.
In Tyndall's experiment a
relevant question for the greenhouse effect is this: can the gas target emit
backradiation back to the heat source making it warmer than before?
In greenhouse theory the answer
to this question is yes: the cooler sky above will backradiate to the surface
below and warm it to a new higher temperature.
In Tyndall's experiment if the greenhouse effect were real the heat
source would get slightly hotter due to the gas tube's backradiation.
Unfortunately for greenhouse
theorists the answer to this question is no: the heat source isn't warmed at
all by the gas tube's backradiation, just as the ground isn't warmed at all by
the sky's backradiation [4].
Yet, for the purpose of
information, let us assume that the greenhouse effect is real and that the gas
tube can warm the heat source up just a little bit. In that case the heat source becomes warmer
than it initially was and so emits EMR at a greater rate.
Due to this increased EMR from
the heat source the tube heats up a bit more than originally, and so in turn
heats up the heat source a bit more, until you have more heat and temperature
merely by putting the gas tube in the proximity of the heat source.
Figure 6: Ever expanding and multiplying reverberations of EMR between these two objects makes the room hotter than originally; impossible, but true according to the greenhouse effect!
In other words by putting the gas
tube in the room, the room is now warmer than it otherwise would be without the
gas tube. How does the gas tube possess
such an energy-creating quality?
Similarly, how can greenhouse gases provide extra heat energy in the
atmosphere? According to thermodynamics
it can't.
At this point some might say that
the atmosphere acts as a blanket, that it traps energy. That only works for blocking convection, i.e.
blocking the physical movement of molecules.
EMR can't be trapped in the same way -- not in an energy sense anyway, because
every ray that is absorbed is countered by a re-emitted one. Greenhouse gases don't act like a real,
physical blanket which blocks convection.
Tyndall believed in the idea of
an atmospheric blanket. Problem is, it
would only make sense if the earth was a significant source of heat; that is if
heat came from inside of the earth and radiated outward. And even then the atmospheric blanket would
have to block convection.
Clouds block convection.
That's why cloudy nights are warmer than cloud
free ones, not because they block and re-radiate heat (as EMR) back to the earth. This entire
Fallacy series is dedicated to dispelling misnomers like these.
Figure 7: Wrong.
Let's follow the reasoning of the blocking/emitting theory (example
here from
USA Today). Instead of the EMR leaving earth, it gets trapped and turns into heat in the cloud. This warms up the water droplets of the cloud. This warmth is then imparted back to the earth to make it warmer than otherwise...and we're back to creating energy again; in other words, it is impossible -- just as impossible as creating energy for free via the greenhouse effect.
Clouds trap heat exactly like a human blanket, blocking the movement of air, stopping the warmer lower layers from convecting higher to cool by mixing especially in the vertical direction. Once the EMR leaves the ground it does not matter to the temperature of the ground whether it is subsequently absorbed on the way out or not [5].
The only effect clouds can have on EMR is to change earth's albedo by changing its emissivity. (This may be possible, I don't know, I haven't looked into it.)
And a cloud could make the surface warmer if it got warmer than it. But even then the effect is, in an energy sense, neutral, because the energy to make the cloud was extracted from the ground in the first place.
Water vapour also keeps the night warmer
by changing the atmospheric lapse rate due to its high latent heat of
evaporation. Greenhouse gases on the other
hand (other than water vapour), neither block convection nor change the adiabatic lapse rate of the air, therefore they
can't block or multiply heat or energy in the air.
[1] John Tyndall,
the Bakerian Lecture:
On the Absorption and Radiation
of Heat by Gases and Vapours, and on the Physical Connexion of Radiation,
Absorption, and Conduction. -- Philosophical
Transactions of the Royal Society of London, Vol. 151 (1861), pp. 1-36.
