How to Fool Yourself with a Pyrgeometer
CO2 alarmism feeds on an idea of massive backradiation or Downwelling Longwave Radiation DLR from the atmosphere to the Earth surface, about 330 W/m2 to be compared with 170 W/m2 absorbed shortwave radiation from the Sun.
DLR thus triples the radiation from the Sun to an alarming 500 W/m2 hitting the Earth surface. This should make it possible to boil eggs on the bare ground, but since this does not work out, we ask: What is the evidence that there is massive DLR?
The answer by a CO2 alarmist is: DLR exists because you can measure it, e.g. it by a pyrgeometer:
•a device that measures the atmospheric infra-red radiation spectrum that extends approximately from 4.5 µm to 100 µm. Here is how it works according to Wikipedia:
The atmosphere and the pyrgeometer (in effect the earth surface) exchange long wave IR radiation. This results in a net radiation balance according to:
Where:
Enet - net radiation at sensor surface [W/m²]
Ein - Long-wave radiation received from the atmosphere [W/m²]
Eout - Long-wave radiation emitted by the earth surface [W/m²]
The pyrgeometer's thermopile detects the net radiation balance between the incoming and outgoing long wave radiation flux and converts it to a voltage according to the equation below.
Where:
Enet - net radiation at sensor surface [W/m²]
Uemf - thermopile output voltage [V]
S - sensitivity/calibration factor of instrument [V/W/m²]
The value for S is determined during calibration of the instrument. The calibration is performed at the production factory with a reference instrument traceable to a regional calibration center.[1]
To derive the absolute downward long wave flux, the temperature of the pyrgeometer has to be taken into account. It is measured using a temperature sensor inside the instrument, near the cold junctions of the thermopile. The pyrgeometer is considered to approximate a black body. Due to this it emits long wave radiation according to:
Where:
Eout - Long-wave radiation emitted by the earth surface [W/m²]
σ - Stefan-Boltzmann constant [W/(m²·K4)]
T - Absolute temperature of pyrgeometer detector [kelvins]
From the calculations above the incoming long wave radiation can be derived. This is usually done by rearranging the equations above to yield the so called pyrgeometer equation by Albrecht and Cox.
Where all the variables have the same meaning as before.
As a result, the detected voltage and instrument temperature yield the total global long wave downward radiation.
So now we now how DLR is measured. Does this mean that DLR exists as a physical transfer of energy from atmosphere to Earth surface? No, it does not as explained as myth of backradiation or DLR. We recall:
A pyrgeometer measures a net transfer and then invents DLR by adding the net to outgoing radiation according to Stefan-Boltzmann for a blackbody emitting into a void at 0 K.
We see that a pyrgeometer does not measure DLR directly but invents it from the formula
•E_in = E_net + E_out,
which is supposed to result from E_net = E_in - E_out expressing a Stefan-Boltzmann law of the form
•E_net = sigma Ta^4 - sigma Te^4,
where Ta and Te are the temperatures of atmosphere and Earth surface. But Stefan-Boltzmann's law is not described this way in physics literature, where it instead takes the form
•E_net = sigma (Ta^4 - Te^4),
which does not allow extracting DLR as sigma Ta^4.
DLR and backradiation is thus fiction invented from an ad hoc formula without physical reality, which is not described in the physics literature. Nevertheless there are companies selling pyrgeometers at price of 4.000 Euro, but of course selling fiction can also serve as a business idea. But is it legal to sell fiction as science? As science fiction?
To sum up: Working with fictional differences of massive gross flows feeds alarm, while physically correct net flow does not.
