It is remarkable that in the climate science debate, the ideal gas law and its consequences in dynamic systems has been variously forgotten, misinterpreted, denied and ignored. In order to clear up the misconceptions, obfuscations , ignorance, error, and denial, it is time to do some practical science in order to lay the various misapprehensions and mis-statements to rest.
It’s very encouraging to see that ‘Lucy Skywalker’ is intending to replicate the experimental work of Roderich Graeff. This is a serious undertaking and a difficult task, due to the very accurate measurement of small differences required. I have decided the Talkshop is going to enter the fray with some empirical experimental work too. The aim is somewhat simpler. We are going to measure the effect of Pressure on a contained volume of air which has energy passing through it, as per Ned Nikolov and Karl Zeller’s outline of the situation in Earth’s atmosphere, which is a volume of air contained by gravity, with sunlight passing through Earth’s day side. This is so we can determine whether there is merit in their hypothesis that the atmospheric temperature profile is underpinned by the effect of gravity on atmospheric mass: warm near the surface where the air pressure is around 14 psi, and cold at high altitude, where the air pressure drops nearly to zero.
Talkshop regulars will remember that a few months back, contributor Konrad Hartmann performed an experiment using pet bottles in direct sunlight. There was some constructive criticism of his experiment, and he made some design improvements which we are awaiting results from. Konrad tested the effect of increased pressure. Initially, we will go the other way, and see what happens when we reduce pressure towards vacuum. After that we will test positive pressures too.
I have been scouring ebay for the equipment we will need to accomplish the task. So far I have a pack of 20 5W ceramic resistors to make a controllable and accurately measurable heat source. And I have also scored a very nice old vacuum pump. This was a real bargain. It’s a Leybold Heraeus, a veritable piece of German precision engineering.
Although it won’t achieve a really hard vacuum, it will get near enough to find out what sort of relationship exists between pressure and temperature as we change the pressure from near vacuuum to ordinary atmospheric levels. John, the ebay seller, very kindly reduced his price when I went to pick it up (it was too heavy for the postal service), when I told him it was for non-profit experimental work.
I’m also awaiting the arrival of another bargain – a Siemens pressure sensor which is insensitive to temperature changes.
It works on the principle of piezo resistivity, using a hybrid ceramic diaphragm to transmit the pressure from the test medium. Full spec here. These are expensive sensors. The new price is 391 Euros. I just won a brand new in-the-box 0-4bar P4 model for £5 on the ‘bay – my favourite shopping channel. :)
For the pressure vessel, I intend to use an old ‘camping gaz’ butane cylinder. This is small enough for vacuum pumping times to be reasonable, and large enough for the required separation between heat source and thermistor.
Which brings me to the measurement side of the experimental set-up.
I have found a neat little four input oscilloscope/datalogging module.
This comes with free software and connects to a USB port. Amplification will be needed for the thermistor signal, and a small power supply for this and the the pressure sensor. I intend to build all this into an old SCSI external hard drive enclosure to keep things neat. More on the construction of this unit once I have all the necessary components in stock.
All this effort is being undertaken in the spirit of Einstein’s famous injunction:
Experimentum Summus Judex – experiment is the final arbiter.
It the climate science arena, we have witnessed how computer model output resting on untested theory has been put forward as scientific truth. This is a fallacy, because ultimately, hypothesis is mere conjecture until experiments are designed and carried out. If experimental results support the hypothesis, it may go forward to become a fully fledged theory.
We are going back to basics here and doing some real science. Before we conduct the experiments, we will make predictions from our hypothesis, and test them properly. All ideas and input from Talkshop contributors and the wider scientific community are welcome. We want to do this as well as we can within the budgetary constraints imposed on non-institutional research.